thin films via epitaxial strain*

Berry curvature of an electronic band structure underlies the calculation of intrinsic anomalous Hall conductivity (AHC) and ferroelectric polarization of quantum materials. However, Berry curvature is highly sensitive to subtle changes in electronic band structure and therefore can be manipulated through external stimulus. Transition metal oxide SrRuO3 provides an ideal material platform to study fine-tuning of Berry curvature. In this work, we carry out systemic transport studies and first-principles calculations to investigate the change in AHC of SrRuO3 thin films both under compressive and tensile strains. We find that as the applied strain changes from compressive to tensile, the magnetic easy axis of SrRuO3 rotates from out-of-plane to in-plane. In the meantime, the sign of AHC changes from negative to positive at low temperatures. In addition, we find that under tensile strain, the AHC of SrRuO3 thin films exhibits a characteristic hump feature, which we attribute to the rotation of Ru magnetic moment. Using Berry curvature calculations, our first-principles simulation reproduces the strain-driven sign change in AHC and the non-monotonic dependence of AHC on Ru magnetic moment when SrRuO3 thin films are under tensile strain.