Low Temperature Specific Heat of the High Tc Superconductors RBa2Cu3O7-δ(R=Y or a Rare Earth Element)

楊國楠(K. N. Yang) ； J. M. Ferreira ； B. W. Lee ； Y. Dalichaouch ； M. S. Torikachvili ； M. B. Maple

《Chinese Journal of Physics》 26卷1S期 (1988/02) Pp. 130-139

並列摘要

Low temperature specific heat C measurements have been made on the high Tc superconductors RBa2Cu3O7-δ(R=rare earth andδ≈0.1) for 0.5 K≦T≦30 K. For YBa2Cu3O7-δ and EuBa2Cu3O7-δ, C(T) consists of phonon and electron contributions only, consistent with the J=0 ground states of the Y3+ and Eu3+ ions. The C(T) data for the RBa2Cu3O7-δ compounds with R=Ho, Tm, and Yb exhibit no features due to magnetic ordering for T＞0.5 K, but reveal Schottky specific heat anomalies which arise from the splitting of the Hund's rules ground state multiplet of the R3+ ions by the crystalline electric field. Specific heat anomalies associated with the long-range magnetic ordering of the R3+ ions, apparently due to dipolar interactions, were observed for the compounds with R=Nd, Sm, Gd, Dy, and Er at TM=0.52 K, 0.61 K, 2.25 K, 0.90 K, and 0.60 K, respectively.