Hysteretic Magnetoresistance in Nd1-xSrxMnO3 Films with Controlled Carrier Density

Magnetotransport characteristics and their nominal hole concentration (x) dependence were investigated in Nd1- x Sr x MnO3 films. Thermal hysteresis in resistivity indicating the occurrence of a first-order phase transition was observed for x=0.35 and 0.50, but essentially not for x=0.40 and 0.45. The x=0.35 and 0.50 films also show hysteresis in magnetoresistance. Once the resistivity is decreased by an order of magnitude by application of a magnetic field, the low-resistivity state is maintained even after removal of the field below a critical temperature. Observed hysteretic behavior suggests the presence of instabilities which compete with double-exchange interaction in specific hole concentration regions, which may be one of the origins of the colossal magnetoresistance.