二维体系的超导转变温度

THE TRANSITION TEMPERATURE OF SUPERCONDUCTIVITY IN TWO-DIMENSIONAL SYSTEMS

如何解释氧化物超导体的高 T_c,是目前高温超导研究的主要任务之一。由于所发现的氧化物超导体具有二维的结构特征,态密度的 Van Hove 奇异性的作用又重新引起注意。本文较为严格地求解了决定 T_c 的积分方程,结果表明态密度的 Van Hove奇异性虽然可以提高 T_c,但并不如人们所估计的那么显著。

In this paper,the enhancement of transition temperature due to Van Hove singularity is exam- ined carfully.The gap equation has been solved rigorously by complex integral method.The derived Tc formula has the self-consistent form and depends on the ratio of Debye temperature and Fermi energy.Numerical examples show that the enhancement of transition temperature is not as effective as estimated before.The conclusion has therefore been made that it seems unlikely that the Van Hove enhancement mechanism is responsible for oxides superconductors.