Pressure effects on the first order transition in MnFe(P,As) and MnFe(P,Ge)

Abstract We report pressure effects on the first-order ferromagnetic–paramagnetic transition in MnFe(P,As) and MnFe(P,Ge). With increasing pressure up to 1.5 GPa, T C increases by 5% for MnFe ( P 0.54 As 0.46 ) but decreases by 2% for MnFe ( P 0.85 Ge 0.15 ) . The divergence of T C as a function of pressure suggests that the dominant parameter determining T C is not the volume, but probably the anisotropic lattice distortion. The magnetization vs temperature hysteresis was increased with applying pressure for MnFe ( P 0.85 Ge 0.15 ) .