Magnetoresistance relaxation in thin La-Sr-Mn-O films exposed to high pulsed magnetic fields

Abstract

The results of investigation of colossal magnetoresistance relaxation in nanostructured La-Sr-Mn-O films after removal of magnetic field pulse are presented. The 400 nm thick films grown by MOCVD technique were studied in the magnetic field range of 2-10 T and temperature range of 100-290 K using a pulsed magnetic field generator based on capacitor bank discharge. A special design of magnetic coil with nonmetallic outer casing made from polyamide material allowed to distinguish relaxation processes occurring in three different time scales: ultrafast (< 1 microseconds), fast (~ 100 microseconds), and slow (~ 1 ms). The dynamics of fast relaxation was analysed using Kolmogorov–Avrami–Fatuzzo model, taking into account reorientation of magnetic domains into equilibrium state. The slow relaxation was analysed by Kohlrausch–Williams–Watts model, considering short-range interaction of magnetic moments in disordered grain boundaries having spin-glass properties.