Superconductivity and isotope effect in iron-based superconductors
报告人:
陈仙辉
中国科技大学物理系 教授
报告时间:
2009-04-02 16:00
报告地点:
郑裕彤讲堂
主办单位:
物理系
简介:
报告摘要：The recent discovery of superconductivity in iron-oxypnictides with TC higher than the McMillan limit of 39 K has generated great excitements. Theoretical calculations indicate that the electron-phonon interaction is not strong enough to give rise to such high TC, while strong ferromagnetic-antiferromagnetic fluctuations have been proposed to be responsible. However, superconductivity and magnetism in pnictide superconductors show a strong sensitivity to the lattice, suggesting a possibility of unconventional electron-phonon (e-p) coupling. In this talk I will mainly present our recent results on the effect of isotope on TC and spin-density wave (SDW) TSDW in pnictides by either oxygen isotope or iron isotope exchange. The results show that oxygen isotope effect on TC and TSDW is very small, while the iron isotope exponent is about 0.35, being comparable to 0.5 for the full isotope effect. Surprisingly, the iron isotope exchange shows the same effect on TSDW as TC. These results indicate that electron-phonon interaction plays some role in the superconducting mechanism, but simple electron-phonon coupling mechanism seems to be rather unlikely because a strong magnon-phonon coupling is included.
