Lattice Effects and the Metal-Insulator Transition: Ca2RuO4 and Beyond


Many transition metal oxides exhibit metal-insulator transitions that are driven by electron-electron interactions but 

also involve significant changes in local lattice structure. Focussing on the specific example of Ca2RuO4 (where the 

symmetry does not change across the transition) we derive an expression for the lattice contribution to the energetics 

of the metal-insulator transition. By combining experimental data with density functional and dynamical mean field 

calcluations we show that the lattice energy is as important as the electronic contribution.  Consequences for the strain dependence of the metal-insulator 

transition are determined and it is shown that films epitaxially grown on substrates typically will not exhibit metal-insulator 

transitions.  Generalization to other materials is outlined.


This work was performed in collaboration with Qiang Han (Columbia University) and was supported by 

the Basic Energy Sciences program of the US Department of Energy under grant DOE-ER-046169 

28 Nov 2017
215 Sharp Lab
A.J. Millis, Dept. of Physics, Columbia University and Center for Computational Quantum Physics, The Flatiron Institute