Electric-field-induced modulation of the anomalous Hall effect in a heterostructured itinerant ferromagnet SrRuO3

Abstract

We fabricated electric-field-effect transistor structures with a channel layer of an itinerant ferromagnet ${\mathrm{SrRuO}}_{3}$ (SRO) heterostructured with a cap layer of ${\mathrm{BaTiO}}_{3}$ and investigated the electric field effects on the anomalous Hall effect (AHE) in SRO. We show that by applying positive and negative gate voltages (${V}_{\mathrm{G}}$), the anomalous Hall conductivity in the heterostructured SRO increases and decreases, respectively, regardless of its sign, while no change in the magnetic easy axis direction is observed. The results indicate that the observed ${V}_{\mathrm{G}}$-induced modulations of the AHE do not simply originate from changes in the magnetization and magnetic anisotropy and indicate that ${V}_{\mathrm{G}}$-induced changes in an integral of the Berry curvature over the filled electronic states play a key role in the observed electric field effects on the AHE in SRO. We also found that ${V}_{\mathrm{G}}$-induced modulations on the AHE are negligibly small for transistor structures with a SRO channel having no BTO cap layer. This implies that the cap-layer-induced modifications in the Ru-O-Ru bond angles in the channel affect the Berry phase, enhancing the electric field effects on the AHE in SRO.