STUDY OF THE INFLUENCE OF THE MAGNETOELASTIC ENERGY IN DRIVING THE MAGNETIC AND STRUCTURAL TRANSITION IN TBCU

TbCu suffers a structural transformation at T(N) = 117 K, with the establishment of a collinear antiferromagnetic order. On the other hand, YCu is a Pauli paramagnet, which also transforms structurally at T(s) = 150 K. In order to test the influence of the magnetoelastic energy as the driving mechanism of the transition in TbCu, we have performed neutron diffraction experiments on the compound Tb0.6Y0.4Cu. From the thermal evolution of the structural and magnetic peaks, we have observed that both, structural (T(s)) and magnetic transitions (T(N)), occur at different temperatures. This separation in the transition temperatures constitutes a strong indication that magnetoelastic energy is not responsible for the transition in TbCu, in spite of the large magnetostriction observed at low temperatures at the metamagnetic field induced transition.