Electrically switchable and tunable rashba-type spin splitting in covalent perovskite oxides

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Varignon, Julien
Bibes, Manuel
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American Physical Society
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In transition-metal perovskites (ABO_3) most physical properties are tunable by structural parameters such as the rotation of the BO_6 octahedra. Examples include the Neel temperature of orthoferrites, the conductivity of mixed-valence manganites, or the band gap of rare-earth scandates. Since oxides often hold large internal electric dipoles and can accommodate heavy elements, they also emerge as prime candidates to display Rashba spin-orbit coupling, through which charge and spin currents may be efficiently interconverted. However, despite a few experimental reports in SrTiO_3-based interface systems, the Rashba interaction has been little studied in these materials, and its interplay with structural distortions remains unknown. In this Letter, we identify a bismuth-based perovskite with a large, electrically switchable Rashba interaction whose amplitude can be controlled by both the ferroelectric polarization and the breathing mode of oxygen octahedra. This particular structural parameter arises from the strongly covalent nature of the Bi-O bonds, reminiscent of the situation in perovskite nickelates. Our results not only provide novel strategies to craft agile spin-charge converters but also highlight the relevance of covalence as a powerful handle to design emerging properties in complex oxides.
©2019 American Physical Society This work has been supported by the European Research Council (ERC) Consolidator Grant MINT under the Contract No. 615759. Calculations took advantage of the Occigen machines through the DARI project EPOC No. A0020910084 and of the DECI resource FIONN in Ireland at Irish Centre for High-End Computing (ICHEC) through the PRACE project FiPSCO. J. V. acknowledges technical help from Adam Ralph from ICHEC.