Electric and magnetic properties of Cu-doped La–Sr manganites
M. S. Reis (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=27983&_origin=article&_zone=art_page&_linkType=scopusAuthor********s&_targetURL=http%3A%2F%2Fwww.scopus. com%2Fscopus%2Finward%2Fauthor.url% 3FpartnerID%3D10%26rel%3D3.0.0%26so rtField%3Dcited%26sortOrder%3Dasc%2 6author%3DReis,%2520M.%2520S.%26aut horID%3D7102676479%26md5%3D0c90c45b 12e038fe0995ca7f44edecb2&_acct=C000012438&_version=1&_userid=4187955&md5=5ce4d28d0b8d4d7db3759d96a80f766 b)http://www.sciencedirect.com/scidirimg/entities/REcor.gif (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#m4.cor*), http://www.sciencedirect.com/scidirimg/entities/REemail.gif (
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a Centro Brasileiro de Pesquisas, Físicas-DME, Rua Dr. Xavier Sigaud 150 Urca, Rio de Janeiro, RJ, 22290-180, Brazil
b Departamento de Física - Universidade Federal do Espírito Santo, Vitória - ES, 29060-900, Brazil
Available online 7 December 2001.
Abstract
Samples of La0.89Sr0.11Mn1−yCuyO3+δ (y=0.00, 0.07) were prepared and characterized by magnetic and transport measurements and zero-field nuclear magnetic resonance. All samples displayed ferromagnetic ****llic behavior below the ordering temperature, which decreased for the Cu-doped sample. 139La NMR spectra have been observed around 19 MHz for both samples, with remarkable broadening and splitting introduced by the Cu doping. An estimate of the magnetoresistivity and magnetocaloric properties was provided as well.
Author Keywords: Magnetic oxides; Magnetic measurements; Electrical resistivity; Magnetoresistance; NMR
Article Outline
• References (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bibl1)
The mixed valence manganites RE1–xAExMnO3 (RE=trivalent rare-earth or Y, AE=divalent alkaline earth) have attracted a lot of scientific interest in the recent years due to their intriguing electronic/magnetic phase diagram and also due to their outstanding magnetotransport properties (see for example Ref. [1 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib1)]). As the electronic and magnetic properties of the manganites are mainly governed by the oxygen-mediated Mn interaction, the substitution of transition ****ls like Cr, Fe, Co, and Cu for Mn in such systems has been extensively investigated, in order to obtain information on the details of that interaction [2 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib2), 3 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib3) and 4 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib4)]. Particularly in the system La1–xSrxMn1−yCuyO3, the introduction of Cu2+ was shown to lead to important changes in the transport properties, with the report of an anomalous conduction mechanism introduced in the Cu–O–Cu chains and possible electronic phase separation [4 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib4), 5 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib5) and 6 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib6)]. In this work, we report preliminary electric and magnetic as well as nuclear magnetic resonance (NMR) measurements in La0.89Sr0.11Mn1−yCuyO3+δ samples, from which one can examine the effect of the Cu substitution on local structure and also on transport properties of the studied manganites.
Bulk samples of La0.89Sr0.11Mn1−yCuyO3+δ (y=0.00, 0.07) were produced by standard solid-state reaction of high-purity La2O3, SrCO3, MnO2 and CuO powders mixed in stoichiometric proportions. The mixed powder was pressed into pellets and first heat-treated at 930°C in atmospheric air for 4 days with three intermediate crushing/pressing procedures. Later, the pellets were heat-treated at 1350°C under oxygen flow for 48 h, with one intermediate crushing and pressing. X-ray diffraction (XRD) indicated the formation of single-phase samples (rhombohedral cell). Scanning electron microscopy (SEM) showed the formation of crystals with dimensions around 2 μm and energy dispersive X-ray (EDS) analysis indicated a nearly homogeneous composition similar to the stoichiometric one.
The real part of the AC magnetic susceptibility (χAC) vs. T curves (recorded with Hrms=0.08 Oe, f=423 Hz) for the as-prepared samples is shown in Fig. 1 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1). The La0.89Sr0.11MnO3+δ sample presents a strong ferromagnetic transition just above room temperature (TC=311 K, from the peak of the dχAC/dT vs. T curve). From this value we can estimate the Mn4+ concentration in this sample to be around 0.20 [7 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib7) and 8 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib8)], which is due both to the Sr substitution for La and also to the cation vacancies associated with the oxygen excess (δhttp://www.sciencedirect.com/scidirimg/entities/223c.gif0.05) in the chemical structure, introduced by the rich-oxygen atmosphere employed during the sample preparation [9 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib9)].
http://www.sciencedirect.com/cache/MiamiImageURL/B6TJJ-44M2GM2-P-H/0?wchp=dGLzVlb-zSkWb (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig1&_ba=1&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=f92c92b21a2b7cb0ba76c9fb41a958f 1)Full-size image (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig1&_ba=1&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=f92c92b21a2b7cb0ba76c9fb41a958f 1) (7K)Fig. 1. Real part of the AC magnetic susceptibility (χAC) vs. T and its first derivative (dχAC/dT) vs. T curves for (a) La0.89Sr0.11MnO3+δ and (b) La0.89Sr0.11Mn0.93Cu0.07O3+δ.
View Within Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1)
The decrease of the magnetic ordering temperature caused by the Cu substitution [5 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib5)] is observed in the χAC vs. T curve shown in Fig. 1b (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1). The 7% Cu-doped sample displays two consecutive transitions, which can be clearly identified as the peaks at 245 and 211 K in the dχAC/dT vs. T curve. As the possibility of impurity phases can be disregarded from the absence of spurious XRD peaks, it must be inferred that one is dealing with genuine magnetic and/or structural transitions. In fact, the existence of such a double transition is also detected, with less evidence, in the undoped sample, as can be observed in the dχAC/dT vs. T curve shown in Fig. 1a (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1). It is worth noting that the observation of such anomalies in χAC vs. T curves is only possible in our case due to the low applied magnetic field employed in the AC magnetic susceptibility measurements. We have verified that, when a DC magnetization measurement is performed for the undoped sample, even the use of a magnetic field around 10 Oe is sufficient to mask the double peak in the derivative curve. On the other hand, the existence of the double transition can be also observed for similar compounds reported in the literature, when an appropriate low field magnetic susceptibility curve is available [9 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib9)]. We can conclude therefore that the behavior displayed in Fig. 1b (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1) is not exclusively due to the Cu substitution, but there is no doubt that the presence of Cu makes the double transition much more obvious than in undoped samples.
Additional information on the magnetic properties of such materials can be attained from the analysis of the magnetization data. Fig. 2 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig2) shows the temperature dependence of the product (∂M/∂T)×H for undoped and 7% Cu-doped samples under magnetic fields H up to 50 kOe (measurements performed in an SQUID). From the integral of (∂M/∂T) with respect to the applied magnetic field one can compute the values of the magnetic entropy change accompanying the magnetic transition [10 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib10)]. The maximum values (around TC) found for 50 kOe of magnetic field change are −3.5 and −3.3 J/kg K for the samples with 0% and 7% of Cu, respectively. These results are in good accordance with previous reports on other manganites [10 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib10) and 11 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib11)], and it is clearly seen that the Cu substitution (at least in the light doping regime) has little influence on the magnetocaloric properties of the studied manganites. The effect of the applied magnetic field on the double transition is also observed in Fig. 2 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig2). The dotted lines indicated in the figure correspond to the transition temperatures derived from χAC data (Fig. 1 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1)). It can be seen that the application of increasing magnetic fields shifts the transitions to higher temperatures, particularly for the Cu-doped sample. At the same time, the existence of two peaks in the (∂M/∂T)×H vs. T curves, which is evident for low fields in the Cu-doped sample case, ceases to be clear for the high magnetic fields, as can be observed in the curves recorded under 50 kOe field.
http://www.sciencedirect.com/cache/MiamiImageURL/B6TJJ-44M2GM2-P-K/0?wchp=dGLzVlb-zSkWb (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig2&_ba=2&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=e83c6dcf8d328d7b60f84adeecc46c4 e)Full-size image (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig2&_ba=2&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=e83c6dcf8d328d7b60f84adeecc46c4 e) (12K)Fig. 2. Magnetic measurements, plotted as (∂M/∂T)×H vs. T curves under various applied magnetic fields for (a) La0.89Sr0.11MnO3+δ and (b) La0.89Sr0.11Mn0.93Cu0.07O3+δ.
View Within Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig2)
The electrical resistivity (ρ), measured with a standard four-probe AC technique under magnetic fields up to 50 kOe, is shown in Fig. 3 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig3) for the 7% Cu-doped sample. The ****l-insulator transition is observed immediately below the ferromagnetic ordering detected from χAC data (Fig. 1 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig1)), giving rise to the maximum observed for ρ around 245 K. With the application of magnetic fields the electrical resistivity decreases, as expected, resulting in a magnetoresistance ratio of 75% at 245 K and 50 kOe. At the same time, the maxima of the ρ vs. T curves are shifted to higher temperatures, in accordance with the magnetization results previously discussed. The inset of Fig. 3 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig3) shows the behavior observed at low temperatures. A minimum in the electrical resistivity is observed around 30 K for the measurement made at zero external field, indicating a semiconducting behavior below this temperature; with the application of moderate fields this minimum is easily suppressed. The existence of this magnetic field dependent minimum in the ρ vs. T curve at low temperatures has been reported in a number of other similar samples [3 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib3) and 9 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib9)] and it is considered as a characteristic of polycrystalline manganites, being usually attributed to variable-range hopping of electrons in the region of disordered grain boundaries [12 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib12)].
http://www.sciencedirect.com/cache/MiamiImageURL/B6TJJ-44M2GM2-P-N/0?wchp=dGLzVlb-zSkWb (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig3&_ba=3&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=e5785b771f5711e11a628c6569865dc 2)Full-size image (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig3&_ba=3&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=e5785b771f5711e11a628c6569865dc 2) (6K)Fig. 3. Electrical resistivity (ρ) vs. T curves recorded under various applied magnetic fields for La0.89Sr0.11Mn0.93Cu0.07O3+δ. The inset shows in detail the low-temperature behavior.
View Within Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig3)
The local atomic arrangement in the structure of undoped and Cu-doped samples were investigated by means of 139La NMR and the results are exhibited in Fig. 4 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig4). These spectra were recorded point by point in an automated pulse NMR spectrometer from the spin-echo intensities measured at varying frequencies, with no external applied magnetic field and at a fixed temperature (4.2 K). Both spectra present broad resonance lines in the same frequency range, but the spectrum corresponding to the 7% Cu-doped samples is broader, extending from 12 to 27 MHz, when compared to that of the undoped sample (15–23 MHz). Besides, one can observe a splitting in the case of the doped sample, with two distinct peaks appearing at 18.5 and 20.6 MHz. The occurrence of two distinct magnetic environments for La nuclei in the structure of the La0.89Sr0.11Mn0.93Cu0.07O3+δ sample constitutes an indication of an inhomogeneous spin arrangement in this material, which could be due to an electronic phase separation, as observed in La1–xCaxMnO3 [13 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib13) and 14 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib14)] and in La0.825Sr0.175Mn1−yCuyO3 [5 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bib5)].
http://www.sciencedirect.com/cache/MiamiImageURL/B6TJJ-44M2GM2-P-R/0?wchp=dGLzVlb-zSkWb (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig4&_ba=4&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=8fed94216e27d7e2cd74a060f4a4e45 b)Full-size image (http://www.sciencedirect.com/science?_ob=MiamiCaptionURL&_method=retrieve&_udi=B6TJJ-44M2GM2-P&_image=fig4&_ba=4&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=full&_orig=search&_cdi=5312&_issn=03048853&_pii=S0304885301010058&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=8fed94216e27d7e2cd74a060f4a4e45 b) (5K)Fig. 4. Zero-field 139La NMR spectra recorded at 4.2 K for La0.89Sr0.11MnO3+δ and La0.89Sr0.11Mn0.93Cu0.07O3+δ samples.
View Within Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#fig4)
In summary, we have studied the effects of Cu doping on the electric and magnetic properties of La0.89Sr0.11Mn1−yCuyO3+δ samples. The replacement of Mn by Cu ions leads to drastic changes in magnetic ordering temperatures and in transport properties, with the possible occurrence of an electronic phase separation suggested by NMR results. This subject needs further clarification, and temperature-dependent 139La and 55Mn NMR measurements are being carried out in order to give an additional information on the details of the effect of Cu substitution on the main magnetic interactions that control the physical properties of the studied manganites.
References
1. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib1)Y.Tokura, Y. Tomioka, J. Magn. Magn. Mater. 200 (1999) 1, and references therein.
2. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib2)I.O. Troyanchuk, M.V. Bushynski, N.V. Pushkarev, H. Szymczak and K. Bärner J. Magn. Magn. Mater. 225 (2001), p. 331. Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-42VV78J-3&_user=4187955&_coverDate=12%2F31%2F2001&_fmt=full&_orig=search&_origin=search&_cdi=5312&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=5e27dc0e594d43ce69712214bc49df5 e&ref=full) | http://www.sciencedirect.com/scidirimg/icon_pdf.gif PDF (178 K) (http://www.sciencedirect.com/science?_ob=MiamiImageURL&_imagekey=B6TJJ-42VV78J-3-H&_cdi=5312&_user=4187955&_pii=S0304885301001391&_check=y&_origin=search&_coverDate=12%2F31%2F2001&view=c&wchp=dGLzVlb-zSkWb&md5=7ac8fed377ea83bddb214f6b24e361d 0&ie=/sdarticle.pdf) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0035041773%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D6d9045fe0c5cdfe7cc7 7b47add829463&_acct=C000012438&_version=1&_userid=4187955&md5=56e6d8098d0a124dfb05cf23618b4ed 4) | Cited By in Scopus (9) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0035041773%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D6d9045fe0c5cdfe7cc7 7b47add829463&_acct=C000012438&_version=1&_userid=4187955&md5=d9641d13fdd6fd1b45091509af54d14 6)
3. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib3)M.M. Xavier, Jr., F.A.O. Cabral, J.H. de Araújo, C. Chesman and T. Dumelow Phys. Rev. B 63 (2001), p. 012408.
4. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib4)L. Pi, L. Zheng and Y. Zhang Phys. Rev. B 61 (2000), p. 8917. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.61.8917&_acct=C000012438&_version=1&_userid=4187955&md5=f65e6c89cb0946be547d78a7b978b35 c) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRB%252Fv61%252Fp 8917%252Fpi%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=af800b4ecb5f14bfbaa4502274fa053 6) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0001198043%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D77ac0b89b3797e14ea5 88eb140bb9999&_acct=C000012438&_version=1&_userid=4187955&md5=2772152efb13f73baeb3efbd1e7d779 c) | Cited By in Scopus (76) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0001198043%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D77ac0b89b3797e14ea5 88eb140bb9999&_acct=C000012438&_version=1&_userid=4187955&md5=e224f02acc1a27919cd3bb2c8dcb9cb 9)
5. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib5)L. Zheng, X. Xu, L. Pi and Y. Zhang Phys. Rev. B 62 (2000), p. 1193. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.62.1193&_acct=C000012438&_version=1&_userid=4187955&md5=1a3d6d23d054406e1a0756eb1fb8031 f) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRB%252Fv62%252Fp 1193%252Fzheng%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=5cf6197411bce45569da8bd7693b945 a) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0001385320%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D001fd42ab1e15c845f5 890cc1110c7e5&_acct=C000012438&_version=1&_userid=4187955&md5=1f3c6d947ef5f0cd10031b01515d332 4) | Cited By in Scopus (24) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0001385320%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D001fd42ab1e15c845f5 890cc1110c7e5&_acct=C000012438&_version=1&_userid=4187955&md5=32d035097db9c02c3d4805b34178b38 c)
6. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib6)L. Pi, X. Xu and Y. Zhang Phys. Rev. B 62 (2000), p. 5667. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.62.5667&_acct=C000012438&_version=1&_userid=4187955&md5=92b3d004290f47ece9c9ddff8041e08 2) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0034261425%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D8bca7dd128818432b59 90750a3993c0d&_acct=C000012438&_version=1&_userid=4187955&md5=f27d0b636da731def6f218283618152 5) | Cited By in Scopus (23) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0034261425%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D8bca7dd128818432b59 90750a3993c0d&_acct=C000012438&_version=1&_userid=4187955&md5=013f614d0872e3c93f5725826f8e81a f)
7. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib7)B. Dabrowski, X. Xiong, Z. Bukowski, R. Dybzinski, P.W. Klamut, J.E. Siewenie, O. Chmaissem, J. Shaffer, C.W. Kimball, J.D. Jorgensen and S. Short Phys. Rev. B 60 (1999), p. 7006. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.60.7006&_acct=C000012438&_version=1&_userid=4187955&md5=c5d9f80c76bc97779686d9797f34d1f b) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRB%252Fv60%252Fp 7006%252Fdabrowski%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=d4920963aea190523713712af13a2c6 2) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0041946318%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D981579dbf083fcaf08a 8b750dc13f492&_acct=C000012438&_version=1&_userid=4187955&md5=c274ecd93f4b78a2dbcb50fb2fd5389 e) | Cited By in Scopus (136) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0041946318%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D981579dbf083fcaf08a 8b750dc13f492&_acct=C000012438&_version=1&_userid=4187955&md5=1e61e6b0e1dd6db8911f0c08be1deb5 d)
8. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib8)M. Paraskevopoulos, F. Mayr, J. Hemberger, A. Loidl, R. Heichele, D. Maurer, V. Müller, A.A. Mukhin and A.M. Balbashov J. Phys.: Condens. Matter 12 (2000), p. 3993. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1088%252F0953-8984%252F12%252F17%252F307&_acct=C000012438&_version=1&_userid=4187955&md5=3a71fa800f7b2e3f27927c27ef65c7f f) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0001037179%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Deca8add93af6ad1ef4d 57ed003aa9ea2&_acct=C000012438&_version=1&_userid=4187955&md5=2370dc160179a16afffeafb4a7ce3d2 9) | Cited By in Scopus (68) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0001037179%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Deca8add93af6ad1ef4d 57ed003aa9ea2&_acct=C000012438&_version=1&_userid=4187955&md5=67692a2a36fcc105e0d5a51a9f724ed 9)
9. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib9)J.F. Mitchell, D.N. Argyriou, C.D. Potter, D.G. Hinks, J.D. Jorgensen and S.D. Bader Phys. Rev. B 54 (1999), p. 6172.
10. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib10)Z.B. Guo, Y.W. Du, J.S. Zhu, H. Huang, W.P. Ding and D. Feng Phys. Rev. Lett. 78 (1997), p. 1142. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevLett.78.1142&_acct=C000012438&_version=1&_userid=4187955&md5=aa3ea0a32336e1a57d885ba2630d6fe 0) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRL%252Fv78%252Fp 1142%252Fguo%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=4be0d6af771f23c28fab3590bc1ff09 8) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0039387050%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Deca3c87956404966148 7ba90ec8b11ac&_acct=C000012438&_version=1&_userid=4187955&md5=ba8f7d08b87c86b61edd8ffbb4dabac 8) | Cited By in Scopus (261) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0039387050%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Deca3c87956404966148 7ba90ec8b11ac&_acct=C000012438&_version=1&_userid=4187955&md5=3e1c285001df7264259bba3e526996f c)
11. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib11)X.X. Zhang, J. Tejada, Y. Xin, G.F. Sun, K.W. Wong and X. Bohigas Appl. Phys. Lett. 69 (1996), p. 3596. OJPS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=6&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Flink.aip.or g%2Flink%2F%253FAPL%252F69%252F3596 %252F1%252Fzhang%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=afc7dd97e2b837d5c9524de3fc88b3d 4) | Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1063%252F1.117218&_acct=C000012438&_version=1&_userid=4187955&md5=f9d555a7757dd789582385106905660 b) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0001409184%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D4efc9d77e818afd6d80 98ef885ab66e6&_acct=C000012438&_version=1&_userid=4187955&md5=f0e043be691bb338456569cf1349332 f) | Cited By in Scopus (122) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0001409184%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D4efc9d77e818afd6d80 98ef885ab66e6&_acct=C000012438&_version=1&_userid=4187955&md5=593296338c2a118c8e12e02ed4743df d)
12. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib12)P. Raychaudhuri, P. Taneja, A.K. Nigam, P. Ayyub, R. Pinto and A. Patade Physica B 259–261 (1999), p. 812. Article (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVH-3W90GYJ-DF&_user=4187955&_coverDate=01%2F31%2F1999&_fmt=full&_orig=search&_origin=search&_cdi=5535&view=c&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=a103e153b84004edd4fdbceed286266 a&ref=full) | http://www.sciencedirect.com/scidirimg/icon_pdf.gif PDF (77 K) (http://www.sciencedirect.com/science?_ob=MiamiImageURL&_imagekey=B6TVH-3W90GYJ-DF-7&_cdi=5535&_user=4187955&_pii=S092145269801134X&_check=y&_origin=search&_coverDate=01%2F31%2F1999&view=c&wchp=dGLzVlb-zSkWb&md5=615f3cb83a0e584025d5a8c38201a55 9&ie=/sdarticle.pdf) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-9344268268%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Dc16649bb9df410209ca fac4566d7ec6e&_acct=C000012438&_version=1&_userid=4187955&md5=8da6f02376acb89d90b4ca26e9ade8d 0) | Cited By in Scopus (7) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-9344268268%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Dc16649bb9df410209ca fac4566d7ec6e&_acct=C000012438&_version=1&_userid=4187955&md5=208f446c4d14f442241f9a37d197522 8)
13. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib13)J. Dho, I. Kim and S. Lee Phys. Rev. B 60 (1999), p. 14545. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.60.14545&_acct=C000012438&_version=1&_userid=4187955&md5=a2719eec5db429305a90cd4daa5d77f 7) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRB%252Fv60%252Fp 14545%252Fdho%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=562e2a24e230e9b0bc7ba1d021ec50c 2) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0000312336%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D25379dbf7b5fe6a56ba 6ce60ce8fcda1&_acct=C000012438&_version=1&_userid=4187955&md5=ea3b702cc8e8ad4e1459bfb504e9df9 2) | Cited By in Scopus (29) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0000312336%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3D25379dbf7b5fe6a56ba 6ce60ce8fcda1&_acct=C000012438&_version=1&_userid=4187955&md5=80a78e7a2838976ec4a512fd1239099 9)
14. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-44M2GM2-P&_user=4187955&_coverDate=04%2F30%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1509226057&_rerunOrigin=google&_acct=C000012438&_version=1&_urlVersion=0&_userid=4187955&md5=60695c74e1834253584141699e6893b 9&searchtype=a#bbib14)G. Allodi, R. De Renzi and G. Guidi Phys. Rev. B 57 (1998), p. 1024. Full **** via CrossRef (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=3&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fdx.doi.org% 2F10.1103%252FPhysRevB.57.1024&_acct=C000012438&_version=1&_userid=4187955&md5=052c1391bc785e6f7b2f43557d7f9ab 6) | APS full **** (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=7&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fpublish.aps .org%2Fabstract%2FPRB%252Fv57%252Fp 1024%252Fallodi%26agg%3DSD&_acct=C000012438&_version=1&_userid=4187955&md5=b69605f2a88c56f0350cdba6f4b0ae7 7) | View Record in Scopus (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=655&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Frecord.url%3Feid%3D2-s2.0-0001510085%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Da855ca2627d8a30125a 493380ac12df4&_acct=C000012438&_version=1&_userid=4187955&md5=1af5d89580c52c8fb52b3c2d7bf1a8e 1) | Cited By in Scopus (60) (http://www.sciencedirect.com/science?_ob=RedirectURL&_method=outwardLink&_partnerName=656&_origin=article&_zone=art_page&_targetURL=http%3A%2F%2Fwww.scopus. com%2Finward%2Fcitedby.url%3Feid%3D 2-s2.0-0001510085%26partnerID%3D10%26rel%3 DR3.0.0%26md5%3Da855ca2627d8a30125a 493380ac12df4&_acct=C000012438&_version=1&_userid=4187955&md5=1e9de0fdaa03ccf20b5c14012900442 5)