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arXiv · 1801.06215

Lattice Energetics and Correlation-Driven Metal-Insulator Transitions: The Case of Ca$_2$RuO$_4$

Qiang Han·Andrew Millis
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Abstract

This Letter uses density functional, dynamical mean field, and Landau-theory methods to elucidate the interplay of electronic and structural energetics in the Mott metal-insulator transition. A Landau-theory free energy is presented that incorporates the electronic energetics, the coupling of the electronic state to local distortions and the coupling of local distortions to long-wavelength strains. The theory is applied to Ca$_2$RuO$_4$. The change in lattice energy across the metal-insulator transition is comparable to the change in electronic energy. Important consequences are a strongly first order transition, a sensitive dependence of the phase boundary on pressure and that the geometrical constraints on in-plane lattice parameter associated with epitaxial growth on a substrate typically change the lattice energetics enough to eliminate the metal-insulator transition entirely.

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Qiang Han, Andrew Millis. 2018-08-17. Lattice Energetics and Correlation-Driven Metal-Insulator Transitions: The Case of Ca$_2$RuO$_4$. https://doi.org/10.1103/physrevlett.121.067601

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