Professor Qimiao Si

Rice University

Electronic Correlations and Superconductivity in Iron Pnictides and Selenides

Abstract:

Studies over the past few years on the iron pnictides have opened up many intriguing questions about electronic correlations, magnetism, and superconductivity in these systems. The issues became even more acute with the recent discovery of high Tc superconductivity in the 122 alkaline iron selenides. In this talk, I will discuss several aspects of these issues. One is the description of the iron pnictides as bad metals close to a Mott transition. As a particular consequence, I’ll describe how isoelectronic tuning of the kinetic energy will suppress antiferromagnetic order and give rise to a quantum critical point; this is now verified by experiments in P doped parent iron arsenides [1]. Within the same description, I will consider the implications of the new 122 iron selenides for Mott transition and local-moment magnetism [2]. Finally, I will discuss how this framework makes it natural that the pairing strength of the 122 iron selenides is similar to that of their pnictides counterparts in spite of very different Fermi surfaces [3].

[1] For a recent review, see E. Abrahams and Q. Si, JPCM 23, 223201 (2011).

 

[2] R. Yu et al, PRL 106, 186401 (2011); R. Yu, P. Goswami, and Q. Si, PRB 84, 094451 (2011)

 

[3] R. Yu et al, arXiv:1103.3259; P. Goswami et al, EPL 91, 37006 (2010).