Hyperfine magnetic fields and Curie temperature in the Heusler alloy Ni2MnSn at high pressure

Abstract

The ‘‘hyperfine magnetic field’’- Hhpf at the nuclei of the diamagnetic atoms 119Sn was measured in Heusler alloy Ni2MnSn by Mössbauer absorption spectroscopy for pressures up to 10.8 GPa at room temperature. The pressure dependences of HhpfSn does not show hysteresis and can be fitted by a linear function HhpfSn(P)/HhpfSn(0) =1+kH⋅P with the coefficient kH=−0.095±0.015 GPa−1, where HhpfSn(0)=4.60±0.12T. Diamond anvil cells were used to obtain high pressure at room temperature. The Curie temperature (TC) has been measured (up to 5.2 GPa) in the ‘‘toroid’’ high pressure device using thermal ac susceptibility measurements. That pressure dependence was linear with the coefficient dTC/dP=7.44 K/Gpa [TC(0)=341.3 K]. The compressibility of the sample has been measured by means of resistive strain gauges at hydrostatic pressure up to 9 GPa. The equation (V−V0)/V0=−a⋅P+b⋅P2 has been fitted to the experimental data with the coefficients a=8.64⋅10−3 GPa−1, b=1.13⋅10−4 GPa−2. The drop of the HhpfSn in pressure range 0–10.8 GPa can be explained on the basis of the empirical theory developed by Delyagin, Krylov, and Nesterov [JETP 76, 1049(1980)].