VIOLATION OF THE ZENER POWER-LAW FOR LINEAR MAGNETOSTRICTION IN THE WEAK RANDOM ANISOTROPY TBXY1-XAL2 MAGNETS

The linear magnetostriction lambda(2) been measured in the TbxY1-xAl2 intermetallic compounds. The Zener power law, which gives lambda(2) as proportional to the third power m(3) of the reduced magnetization, is found to be valid in the ferromagnetic phase of TbAl2. For x < 1 the compounds are weak random anisotropy magnets, and in the quasisaturate d regime induced by a magnetic field lambda(2) is still proportional t o m(p), but the exponent p is smaller than three. p increases with the field and approaches three in the high-field limit (12 T). A relation between the violation of the Zener power law and the reduction of the magnetization in the random anisotropy systems is derived, and is com pared with the experimental results.