Condensed Mater Seminar "3d oxide physics without inter-electronic repulsion U"

Alex Zunger, University of Colorado

G126

In his seminal work, N. Mott theorized that the insulating behavior of 3d transition metal oxides emerges from the strong correlation, encoded by the on-site inter-electronic repulsion (“U”) between d electrons. This repulsion keeps the d electrons localized within bands of width W where U>W , and was argued as the correct mechanism regardless of the magnetic order. This picture of doubly-occupied and empty bands is the text book model of (Mott) insulation. At the same time, it created a general position in the literature that mean-field like single determinant approaches such as DFT are inappropriate for describing the broad science issues of 3d oxides, such as catalysis, thermoelectric, photovoltaics, etc. The highly correlated approach builds upon the observation that DFT is inappropriate because it can not explain paramagnetism as a non magnetic state. We explored the alternative option of staying within (single determinant) mean field DFT but getting rid of Naive -DFT approximations by allowing spontaneous symmetry breaking if it lowers the total energy . This generalization creates finite band gaps in AFM and PM phases of ABO3 perovskites (except PM SrVO3 and CaVO3 that are metals), disproportionation (in SmNiO3 and YNiO3), mass enhancement (in SrVO3and doped SrTiO3) and explains the observed trends in JT distortions throughout the series.

Thursday, November 21, 2019 at 12:00pm to 1:00pm

Duane Physics and Astrophysics, G126
2000 Colorado Avenue, Boulder, CO 80309

Event Type

Colloquium/Seminar

College, School & Unit

Arts & Sciences

Group
Physics
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