Magnetoelastic effects in terbium

The variation of the elastic modulus C₃₃ of terbium has been investigated as a function of temperature in the range 200–230 K, which includes the whole of the antiferromagnetic phase, and as a function of magnetic field applied along the easy magnetic direction, the b axis. Hysteresis in C₃₃ in the antiferromagnetic phase is interpreted in terms of spiral spin domains. The magnetic phase changes are reflected in anomalies in the elastic constant and these are used to produce a magnetic phase diagram of terbium. The final phase diagram has been compared with earlier measurements of magnetisation and magnetostriction.