MAGNETOELASTIC INTERACTIONS IN RE2CUO4 SYSTEM

We present thermal expansion data for R2CuO4 (R = Pr, Nd, Sm, Gd, Eu) compounds and specific heat measurements of Sm and Eu compounds in the temperature range from liquid helium to room temperature. In the case of Pr, Nd, Gd, and Eu compounds the coefficient of thermal expansion (alpha) increases monotonously with rising temperature whereas alpha o f the Sm compound shows a pronounced minimum at about 60 K. These find ings are interpreted in terms of the crystal field induced electric qu adrupole moment of the 4f electrons.