A study on the kinetic arrest of magnetic phases in nanostructured Nd_0.6Sr_0.4MnO₃ thin films

The Nd0.6Sr0.4MnO3 (NSMO) manganite system exhibits a phase transition from paramagnetic insulating (PMI) to ferromagnetic metallic (FMM) state around its Curie temperature T-C = 270 K (bulk). The morphology-driven changes in the kinetically arrested magnetic phases in NSMO thin films with granular and crossed-nano-rod-type morphology are studied. The manganite thin films at low temperatures possess a magnetic glassy state arising from the coexistence of the high-temperature PMI and the low-temperature FMM phases. The extent of kinetic arrest and its relaxation was studied using the 'cooling and heating in unequal field (CHUF)' protocol in magnetic and magnetotransport investigations. The sample with rod morphology showed a large extent of phase coexistence compared to the granular sample. Further, with a field-cooling protocol, time-evolution studies were carried out to understand the relaxation of arrested magnetic phases across these morphologically distinct thin films. The results on the devitrification of the arrested magnetic state are interpreted from the point of view of homogeneous and heterogeneous nucleation of the ferromagnetic phase in the paramagnetic matrix with respect to temperature.