报告题目：Physical effects of impurities on electronic structure of Fe-based superconductors

报 告 人：Dr. Wei Ku, Brookhaven National Laboratory

报告时间：12月12日（周三）上午10:30

报告地点：物理系三楼报告厅

报告摘要：Recent theoretical studies of physical effects of impurities on electronic structure of Fe-based superconductors will be presented. With Co- and Zn- substitution of Fe, our result indicates injection of real carriers and thus invalidates recent claim of such substitution being isovalent. On the other hand, a significant shift of chemical potential is found upon disordering the Fe vacancy of K_0.8Fe_1.6As₂, generating an effective “doping” to the system without additional charge carriers. The seemingly absent hole carriers are actually still present in the system, but become incoherent in nature, raising new questions concerning their role in superconductivity. Finally, with isovalent substitution of Fe by Ru, an unexpected insensitivity of the low-energy carriers is found, offering a natural explanation why superconductivity and transport of this material are so resilience to large amount of disordered impurities. Similarity of the underlying mechanism to the exotic super-diffusion mechanism will be discussed.

References:

[1] Phys. Rev. Lett. 109, 147003 (2012)

[2] Phys. Rev. Lett. 108, 207003 (2012)

[3] arXiv:1209.3001; to appear in Phys. Rev. Lett.

[4] Phys. Rev. Lett. 106, 077005 (2011)