Anomalous first-order transition in Nd0.5Sr0.5MnO3: an interplay between kinetic arrest and thermodynamic transitions

A detailed investigation of the first-order antiferromagnetic insulator (AFI) to ferromagnetic metal (FMM) transition in Nd0.5Sr0.5MnO3 is carried out by resistivity and magnetization measurements. These studies reveal several anomalous features of thermomagnetic irreversibility across the first-order transition. We show that these anomalous features cannot be explained in terms of the supercooling effect alone and the H–T diagram based on isothermal M–H or R–H measurements alone does not reflect the true nature of the first-order transition in this compound. Our investigations reveal glass-like arrest of kinetics at low temperature which plays a dominant role in the anomalous thermomagnetic irreversibility observed in this system. The interplay between kinetic arrest and supercooling is investigated by following novel paths in the H–T space. It is shown that coexisting FMM and AFI phases can be tuned in a number of ways at low temperature. These measurements also show that kinetic arrest temperature and supercooling temperature are anticorrelated, i.e. regions which are arrested at low temperature have higher supercooling temperature and vice versa.