Anomalous insulator-metal transition and weak ferromagnetism in Nd0.37Sr0.63MnO3 thin films

TitreAnomalous insulator-metal transition and weak ferromagnetism in Nd0.37Sr0.63MnO3 thin films
Type de publicationJournal Article
Nouvelles publications2008
AuteursPrasad, R, Singh, MP, Siwach, PK, Fournier, P, Singh, HK
JournalEPL (Europhysics Letters)
Volume84
Pagination27003 (6pp)
Résumé
We report thickness-dependent magnetic and transport properties at the boundary separating A- and C-type antiferromagnetic phases in films of the overdoped manganite Nd0.37Sr0.63MnO3. The thin films are prepared by DC magnetron sputtering on single-crystal LaAlO3 substrates. All films, 5-120 nm in thickness, show a paramagnetic-ferromagnetic (PM-FM) transition. The small value of magnetization ([?] 0.45 mB/Mn) is suggestive of the weak nature of the FM correlations that is different from the prototype PM-FM transition due to double exchange (DE). At lower film thicknesses, such as 5 and 25 nm, zero-field resistivity shows an insulator-like behavior. An insulator-metal (IM) transition is observed at higher film thicknesses ([?] 60 nm). The magnetic-field independence of the observed IM transition (TIM[?]125 K) distinguishes it from the same observed in prototype manganites (x[?]0.2-0.4) and explained by DE. For the thinnest films, a CMR effect as large as MR[?]85% is observed in the low-temperature regime. The observed phenomena can be explained in terms of orbital-fluctuation-induced phase separation.
URLhttp://stacks.iop.org/0295-5075/84/27003
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