Light-Induced Mott-Insulator-to-Metal Phase Transition in Ultrathin Intermediate-Spin Ferromagnetic Perovskite Ruthenates.

Liu, Ruxin; Si, Liang; Niu, Wei; Zhang, Xu; Chen, Zhongqiang; Zhu, Changzheng; Zhuang, Wenzhuo; Chen, Yongda et al. · Adv Mater · 2023

basic_science · Level V

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Abstract

Light control of emergent quantum phenomena is a widely used external stimulus for quantum materials. Generally, perovskite strontium ruthenate SrRuO<sub>3</sub> has an itinerant ferromagnetism with a low-spin state. However, the phase of intermediate-spin (IS) ferromagnetic metallic state has never been seen. Here, by means of UV-light irradiation, a photocarrier-doping-induced Mott-insulator-to-metal phase transition is shown in a few atomic layers of perovskite IS ferromagnetic SrRuO<sub>3-</sub> <sub>δ</sub> . This new metastable IS metallic phase can be reversibly regulated due to the convenient photocharge transfer from SrTiO<sub>3</sub> substrates to SrRuO<sub>3-</sub> <sub>δ</sub> ultrathin films. These dynamical mean-field theory calculations further verify such photoinduced electronic phase transformation, owing to oxygen vacancies and orbital reconstruction. The optical manipulation of charge-transfer finesse is an alternative pathway toward discovering novel metastable phases in strongly correlated systems and facilitates potential light-controlled device applications in optoelectronics and spintronics.