Condensed Matter Seminars

Strong electronic correlation lies at the heart of modern condensed matter and material physics. An adequate treatment of the electronic correlation beyond standard band theory is a key to understand many unusual physical properties of strongly correlated materials such as Mott insulators and unconventional superconductors. In this talk, I will show how electronic correlation leads to dramatic modifications of the band theory predictions for the electronic structures in general, and the electron-phonon coupling and spin dynamics in particular in high temperature superconductors. I will demonstrate that first-principles electronic structure methods GW and dynamical mean field theory (combined with density functional theory) can account for the non-local and local electronic correlations, respectively, beyond standard band theory, and are useful tools to understand the microscopic mechanisms of high temperature superconductivity in (Ba,K)BiO3 and iron-based superconductors. For the former, electronic correlation leads to a strong enhancement of the electron-phonon coupling while for the latter, electronic correlation significantly strengthens the low-energy spin excitation, both of which favor higher superconducting temperature. In the end, I will discuss how we may use these first-principles methods to accelerate the discoveries of new functional materials with desired properties.

References:
[1] Z. P. Yin, A. Kutepov, and G. Kotliar, Phys. Rev. X 3, 021011 (2013).
[2] Z. P. Yin, K. Haule, and G. Kotliar, Nat. Mater. 10, 932-935 (2011).
[3] Z. P. Yin, K. Haule, and G. Kotliar, Nat. Phys. 7, 294-297 (2011).
[4] Z. P. Yin, K. Haule, and G. Kotliar, Phys. Rev. B 86, 195141 (2012).
[5] Z. P. Yin, K. Haule, and G. Kotliar, to be published (2013).
[6] Z. P. Yin and G. Kotliar, EPL 101, 27002 (2013).
[7] M. Retuerto et al. Chemistry of Materials, 10.1021/cm402423x (2013).