Field dependence of Young's modulus in a gadolinium single crystal

The field dependence of Young's modulus along the hexagonal c axis is measu red in a gadolinium single crystal over a wide range of temperatures and ma gnitudes of the magnetic field aligned with the c axis. It is found that th e isotherms of the field dependence of the Delta E effect in gadolinium are well approximated by a linear dependence on the square of the magnetizatio n in both strong and weak strong magnetic fields, and also above and below the spin reorientation temperature. It is shown that the experimental trend s obtained near the ferromagnetic transition can be interpreted within the approach based on the Landau theory of second-order phase transitions. The parameters of such an approach are determined for gadolinium on the basis o f the experimental data. (C) 1998 American Institute of Physics. [S1063-776 1(98)01512-1].