Recent developments on the electronic nematicity in iron-based superconductors -- the role of electron correlations

by Prof. Rong Yu (Department of Physics, Renmin University of China)

Wednesday 20 Mar 2019, 13:30 → 15:00 Asia/Shanghai

TDLI

Abstract

Electron order in general, and electronic nematic order in particular, has been the topic of considerable interest in the area of iron-based superconductors. New type of questions continues to emerge. In this talk, I will focus on two recent developments on the electronic nematicity, with a particular attention to the role of electron correlations. In the first example, I will show that the multiorbital aspect of electron correlations, in the form of orbital selectivity, interplays with the nematicity in a striking way in bulk FeSe. [1] A finite nematic order helps to stabilize an orbital selective Mott phase. Moreover, when the various types of bond and site nematic orders are combined, there exists a surprisingly large orbital selectivity between the xz and yz orbitals even though the associated band splitting is relatively small. These results explain the seemingly unusual observation of strong orbital selectivity in the nematic phase of FeSe. [2] In the second example, I will show that, via a Ginzburg-Landau theory with symmetry analysis, the spin correlations in the system allow for a variety of nematic orders, in particular an unusual B2gB2g nematicity. [3] Based on qualitative as well as microscopic calculations, I will discuss the types of magnetic fluctuations that stabilize this B2gB2g nematicity and how our proposed mechanism provides a natural understanding of the recent experimental observations in heavily hole doped iron pnictides (Rb,Cs)Fe22As22. [4, 5]

 

[1] R. Yu, J.-X. Zhu, Q. Si, Phys. Rev. Lett. 121, 227003 (2018).

[2] P. O. Sprau et al., Science 357, 75 (2017).

[3] Y. Wang, W. Hu, R. Yu, Q. Si, arXiv: 1903.00375.

[4] X. Liu et al., arXiv: 1803.07304.

[5] K. Ishida et al., arXiv: 1812.05267.

                                                

 

Welcome to join us!

Biography

Rong Yu is a professor at Department of Physics, Remin University of China. He obtained his Ph.D. degree from University of Southern California in 2007. He was a postdoctoral research associate at University of Tennessee, Knoxville (2007–2009) and at Rice University (2009-2013). He has been working on theory of correlated electronic systems. Current main areas of his research includes superconductivity and correlation effects in iron-based superconductors, frustration and disorder effects in quantum magnets, and phase transitions in heavy fermion systems.  

Division

Condensed Matter