Magnetoelasticity of CoS2

Abstract

Abstract The magnetization of an itinerant ferromagnet CoS2 has been measured in high magnetic fields under high pressures. The Curie temperature, T C = 121 K at ambient pressure decreases with increasing pressure with the rate dT C/dP = −5.1 KGPa−1. The second-order type ferromagnetic transition at T C changes into the first-order type for P ≥ 0.4 GPa, where a metamagnetic transition in magnetic field was observed just above T C From the analysis of the magnetization curve for 1.3 GPa, the Landau expansion coefficients of the magnetic free energy were determined. We found that the second- and fourth-order coefficients tend to change the sign around T C From the thermal expansion measurements, the magnetovolume coupling constant is determined as n dd = (1−2) x 10−3/μ μB −2. This value is consistent with that estimated from the pressure effect on the magnetization at Iow temperatures.