Low-Field Ac Magnetotransport in La0.6Bi0.1Sr0.3MnO3

Abstract

We report temperature and field dependence of ac resistance (Z') and reactance (Z") of La0.6Bi0.1Sr0.3MnO3 in the radio frequency range (f = 0.1-5 MHz) under low dc magnetic fields (H {less than or equal to} 1 kOe). While the Z' in zero field shows a weak peak around the ferromagnetic-paramagnetic transition (TC) for f {less than or equal to} 100 kHz, it shows an abrupt jump around the TC for f = 5 MHz. In contrast, the Z" shows an abrupt increase around the TC for all frequencies. We found a maximum ac magnetoresistance of -24.2% at f = 5 MHz and magnetoreactance of -19.6% at f = 0.1 MHz for ΔH = 500 Oe. In comparison to ac magnetoresistance, the dc magnetoresistance shows similar value for ΔH = 50 kOe. It is suggested that the huge ac magnetoresistance arises from the suppression of ac transverse permeability which results in enhanced electromagnetic skin depth under a magnetic field.