Dynamical magnetotransport in Ln(0.6)Sr(0.4)MnO(3) (Ln = La, Sm)

作者：Naik V B; Rebello A; Mahendiran R^*

来源：Journal of Applied Physics, 2011, 109(7): 07C728.

DOI：10.1063/1.3562517

We compare radio frequency electrical transport in Ln(0.6)Sr(0.4)MnO(3) (Ln = La and Sm). AC resistance (R) and reactance (X) were simultaneously measured as a function of temperature (T), magnetic field (H), and frequency (f). The R(T, H = 0 G) in La0.6Sr0.4MnO3 (LSMO) shows a broad insulator-metal transition around 247 K below the Curie temperature (T-C) for f <= 2 MHz but a steplike increase at TC for f >= 3 MHz. Conversely, R(T, H = 0 G) in Sm0.6Sr0.4MnO3 exhibits a single peak at T-C = 116 +/- 2 K for f = 0.1 MHz which splits into two peaks accompanied by a dip at T-C for higher frequencies. While the low temperature peak shifts upward rapidly with the increasing H (mu H-0 > 1 T) for f = 5 MHz, the high temperature peak is insensitive to the magnetic field. A large ac magnetoresistance (Delta R/R = -32%) and magnetoreactance (Delta X/X = -21%) at a low magnetic field (H = 70 mT) is observed in LSMO around T-C in contrast to a positive Delta R/R (=170%) and a negative Delta X/X (= -94%) at mu H-0 = 7 T. We discuss the possible origins of the observed effects.

• 出版日期2011-4-1