Magnetovolume effects of MnAs1−xSbx

Thermal expansion, high-field magnetization, and susceptibility measurements have been made for MnAs0.7Sb0.3. The thermal expansion measurements show that the spontaneous magnetostriction is large and anisotropic below Tc. The spontaneous magnetostriction at 0 K is estimated to be 1.2×10−2 for a axis, −0.8×10−2 for c axis, and 1.6×10−2 for the volume. The spontaneous magnetization decreases sharply in the narrow temperature region below Tc=230 K. All the spontaneous magnetostrictions are found to be proportional to the square of spontaneous magnetization. The magnetization curves measured in a high field up to 40 T show the metamagnetic-like transitions at temperatures above Tc, and they are almost perfectly reproduced by an equation H=A1σ+A2σ3+A3σ5, where H is the applied field and σ is the relative magnetization.