Strain-induced tuning of the electronic Coulomb interaction in 3d transition metal oxide perovskites

Epitaxial strain offers an effective route to tune the physical parameters in transition metal oxides. So far, most studies have focused on the effects of strain on the bandwidths and crystal field splitting, but recent experimental and theoretical works have shown that also the effective Coulomb interaction changes upon structural modifi- cations. This effect is expected to be of paramount importance in current material engineering studies based on epitaxy-based material synthesization. Here, we perform constrained random phase approximation calculations for prototypical oxides with a different occupation of the d shell, LaTiO 3 (d 1 ), LaVO 3 (d 2 ), and LaCrO 3 (d 3 ), and systematically study the evolution of the effective Coulomb interactions (Hubbard U and Hund’s J) when applying epitaxial strain. Surprisingly, we find that the response upon strain is strongly dependent on the ma- terial. For LaTiO 3 , the interaction parameters are determined by the degree of localization of the orbitals, and grow with increasing tensile strain. In contrast, LaCrO 3 shows the opposite trends: the interactions parameters shrink upon tensile strain. This is caused by the enhanced screening due to the larger electron filling. LaVO 3 shows an intermediate behavior.