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I will discuss two examples of the interplay of distortion and Mott insulator physics. In certain ABO3 perovskite materials including BiNiO3, it is found that the Mott transition is accompanied by a symmetry change and a colossal volume collapse upon entering the metallic phase with pressure or temperature. We show that may be viewed as a new type of “hybridization-switching” Mott transition. In a different setting, the spinel compound NiRh2O4 has been argued to possibly form a S=1 spin liquid state on the diamond lattice. However, we show that the physics in the presence of distortion and spin-orbit coupling is quite distinct, leading to a non-magnetic “atomic” ground state, and we use slave boson theory to discuss its magnetic excitations, make comparison with current experiments, and predict “dark states” which are invisible to neutrons but may be possibly probed using RIXS experiments.

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Arun Paramekanti, University of Toronto
Seminar Room of the Institute of Physics II
Contact: Simon Trebst