|Title||Anomalous insulator-metal transition and weak ferromagnetism in Nd0.37Sr0.63MnO3 thin films |
|Publication Type||Journal Article |
|Year of Publication||2008 |
|Authors||Prasad R, Singh MP, Siwach PK, Fournier P, Singh HK |
|Journal||EPL (Europhysics Letters) |
|Pagination||27003 (6pp) |
|Abstract||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.