The effects of Ge occupation and hydrostatic pressure on the metamagnetic phase transition and magnetocaloric effect in Mn2Sb alloy

Jinsong Zhang,Zixin Chen,Fulong Wei,Qiang Wang,Xiaowei Yin,Shaohui Chen,Xiaomeng Fan,Weibin Cui,Guiquan Yao

doi:10.1063/1.5067001

Abstract

The effects of Ge occupations at Sb and Mn sites in Mn2Sb system had been re-examined along with the influence of hydrostatic pressure. The metamagnetic phase transition from ferrimagnetic (FRI) to antiferromagnetic (AFM) state was observed in Mn2Sb1-xGex (x = 0.05, 0.1) and (Mn1-yGey)2Sb (y = 0.025, 0.04) alloys. The phase transition temperature, Tt, was gradually increased with increased Ge substitution for both Sb and Mn, but slightly decreased under increased hydrostatic pressure in Mn2Sb0.95Ge0.05 alloy. Meanwhile, the slope of critical field as the function of temperature was reduced with increased hydrostatic pressure and Ge substitution amount in (Mn1-yGey)2Sb (y = 0.025, 0.04) alloys. For a field change of 7 T, the maxima of magnetic entropy changes of 6 Jkg-1K-1 and 7.1 Jkg-1K-1 have been achieved in Mn2Sb0.95Ge0.05 and Mn1.95Ge0.05Sb alloys, which are gradually decreased by more Ge substitution and increased hydrostatic pressure.

Highlights

As the global warming caused by the greenhouse effect is increasingly serious
Once the structural transition is concurrent with magnetic transition, which is know as the firstorder magnetic transition (FOMT), the magnetic entropy changes can be maximized but accompanied by the hysteresis
The other is magnetoelastic transition (MET), in which only lattice parameters are changed without crystal symmetry evolution, such as MnFeP0.45As0.5510 and LaFe11.4Si1.6.11 For the materials undergoing MET, smaller thermal/magnetic hysteresises are produced than those possessing magnetostructural transition (MST),12,13 which is attractive for studying

Summary

INTRODUCTION

As the global warming caused by the greenhouse effect is increasingly serious. Compared with the traditional refrigeration technology, the magnetic refrigeration technology, which is based on the magnetocaloric effects (MCEs), has demonstrated obvious advantages and attracted great considerations. The MCE is observed as the changes of magnetic entropy and the adiabatic temperature when the ferromagnet or paramagnet is exposed to a changing external magnetic field. Once the structural transition is concurrent with magnetic transition, which is know as the firstorder magnetic transition (FOMT), the magnetic entropy changes can be maximized but accompanied by the hysteresis. In general, FOMT can be divided into two categories. One is magnetostructural transition (MST), in which magnetism and crystallographic symmetry change simultaneously, such as Gd5Si2Ge28 and MnNiGe:Fe systems.. The other is magnetoelastic transition (MET), in which only lattice parameters are changed without crystal symmetry evolution, such as MnFeP0.45As0.5510 and LaFe11.4Si1.6.11 For the materials undergoing MET, smaller thermal/magnetic hysteresises are produced than those possessing MST, which is attractive for studying. Besides the magnetization change, the changes on magnetoresistivity, lattice parameters are observed, indicating the first-order feature of magnetoelastic transition. In the AFM state, in each Mn sublattice, the moments of magnetic atoms are anti-paralleled, leading to the totally zero net moment. Since the lattice parameters are changed during the phase transition of Mn2Sbbased systems, it is possible to tune the magnetocaloric effect by applying the hydrostatic pressure. The effects of hydrostatic pressure on the metamagnetic transition have been studied

EXPERIMENT

AND DISCUSSION

Findings

CONCLUSION