Giant magnetoresistance associated with a first-order transition between two ferrimagnetic states in Mn_2−xZn_xSb (x < 0.3) compounds

A giant magnetoresistance (GMR) is observed in the Mn(2-x)Zn(x)Sb ( x < 0.3) system, with the largest MR ratio of -37.6% in a field of 5 T at 120K for the Mn(1.9)Zn(0.1)Sb compound. Different from other Mn(2)Sb-based compounds, the GMR in Mn(2-x)Zn(x)Sb is closely correlated with a field-induced transition from a weak ferrimagnetic (WFI) state to a ferrimagnetic (FI) state. It is understood that the influences of both super-zone gap and spin-dependent scattering are responsible for GMR in the present system. Magnetic hysteresis and phase coexistence of the WFI and the FI phases suggest that this WFI-FI transition is of first order. The different mechanisms responsible for butterfly loops of magnetization/resistivity curves in different magnetic states are discussed.