First-order nature of a metamagnetic transition and mechanism of giant magnetoresistance in Mn2Sb0.95Sn0.05

Abstract

Magnetization behavior across a metamagnetic transition from an antiferromagnetic state to a ferrimagnetic state is investigated in detail for compound Mn2Sb0.95Sn0.05. The study clearly brings out various generic features associated with a first-order transition, viz., the appearance of hysteresis and the coexistence of magnetic phases. We also observe that the magnetization versus field butterfly loops occurs, while the virgin curve lies outside the envelope magnetization curve. The electronic specific-heat coefficient at low temperatures increases with increasing applied magnetic field, after the field is larger than the critical transition field. This is direct evidence of the formation of a super-zone gap that yields the change of density of electric states and further proves that the large magnetoresistance effect in intermetallic compounds is originated from the reconstruction of Fermi surface due to the collapse of the super-zone gap after the metamagnetic transition.