Magnetoresistance Relaxation in Thin La-Sr-Mn-O Films Exposed to High-Pulsed Magnetic Fields

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