Specific heat and thermal expansion in Gd_xY_1-xCu₂

Abstract

Specific heat and thermal expansion experiments have been performed on GdxY1-xCu2 compounds between 1.2K and 50K and from 1.4K up to 77K, respectively. The specific heat data are analysed in an electronic, lattice and magnetic part resulting in a gradual variation of the Debye temperature with composition and in a magnetic entropy proportional to the number of Gd atoms. From the thermal expansion data below TN a magnetic contribution to the volume at zero temperature of negative sign is deduced. The magnetic volume is roughly proportional to x2 and is attributed to the loss of short-range polarisation at the antiferromagnetic spin configuration. By comparing the specific heat and thermal expansion data, the electronic, lattice and magnetic Gruneisen parameters have been determined.