Electric Tuning of Magnetic Anisotropy and Exchange Bias of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>0.8</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mrow><mml:mn>0.2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Co</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>0.67</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mrow><mml:mn>0.33</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Mn</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math> Bilayer Films
Jinghua Song, Yuansha Chen, Xiaobing Chen, Tahira Khan, Furong Han, Jine Zhang, Hailin Huang, Ji Ma, Wenxiao Shi, Shaojin Qi, Fengxia Hu, Baogen Shen, Jirong Sun
Abstract
Heterostructures composed of dissimilar perovskite oxides with different properties provide an opportunity to observe emergent phenomena, and have promising applications. A key feature of oxide heterostructures is interfacial electronic and orbital reconstruction. In this paper, we demonstrate a dramatic variation in magnetic anisotropy caused by electric tuning of the charge-transfer process in a ${\mathrm{La}}_{0.8}{\mathrm{Sr}}_{0.2}{\mathrm{Co}\mathrm{O}}_{3}/{\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}\mathrm{O}}_{3}$ bilayer structure. By repeatedly changing the valence state of $\mathrm{Co}$ ions in the ${\mathrm{La}}_{0.8}{\mathrm{Sr}}_{0.2}{\mathrm{Co}\mathrm{O}}_{3}$ top layer using ionic-liquid gating, reversible switching of the magnetic easy axis of the bottom ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}\mathrm{O}}_{3}$ layer between the out-of-plane and the in-plane direction is achieved, accompanying a modulation of the interfacial exchange coupling. $\mathrm{Mn}$-to-$\mathrm{Co}$ charge transfer and its effect on the interfacial orbital occupancy are further confirmed by x-ray absorption spectroscopy and x-ray-linear-dichroism analysis. The considerable interfacial charge transfer causes an overlap of the $\mathrm{Mn}$ and $\mathrm{Co}$ 3d orbitals, resulting in orbital reconstruction in the ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}\mathrm{O}}_{3}$ layer and thus magnetic anisotropy. This work demonstrates a promising method for tuning the orbital occupancy and related properties of perovskite heterostructures.