Magnetic and Structural Properties of Mn_1.8Co_0.2Sb under High Magnetic Fields

Abstract

Magnetization, electrical resistivity and X-ray diffraction measurements were carried out for Mn_1.8Co_0.2Sb with a tetragonal structure in 4.2 ≤ T ≤ 280 K and in field B up to 16 T. For B = 0 T, anisotropic structural deformation occurred at T_t ∼ 140 K for zero-field cooling (ZFC), accompanied by a first-order magnetic transition from the ferrimagnetic (FRI) to antiferromagnetic (AFM) phases. In this deformation, the lattice parameters a and c changed by Δa/a = +0.15% and by Δc/c = −0.44%, respectively. By applying magnetic fields of 5 T, T_t decreased to 60 K with thermal hysteresis of 35 K. The two-phase coexistence of the AFM and residual FRI phases was observed even at 10 K for field cooling of 5 T, while a single phase of AFM was confirmed for ZFC. At B = 16 T, the transition did not occurs. In addition, a field-induced structural deformation was observed, accompanied by the metamagnetic transition just below T_t. The obtained results are discussed from a viewpoint on entropy change for the transition.