Magnetoresistance relaxation anisotropy of nanostructured La-Sr(Ca)-Mn-O films induced by high pulsed magnetic fields

Abstract

The results of investigation of colossal magnetoresistance relaxation in nanostructured La-Sr(Ca)-Mn-O films upon removal of magnetic field pulse are presented. The 280 nm thick films grown by PI MOCVD technique were studied in pulsed magnetic fields having duration of 0.9 ms and amplitudes up to 10 T. It was obtained, that ‘fast’ relaxation process occurring in hundred microseconds time scale exhibits anisotropy: the magnitude of remnant resistivity is 3 times smaller and the process is faster when magnetic field is applied perpendicular to the film plane in comparison with in-plane direction. The dynamics of this relaxation process was analyzed using Kolmogorov–Avrami–Fatuzzo model, taking into account reorientation of magnetic domains into equilibrium state. The ‘fast’ remnant relaxation was not observed after the application of longer pulses (20 ms) having amplitude of 60 T.