Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7
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The interplay between spin–orbit coupling and structural inversion symmetry breaking in solids has generated much interest due to the nontrivial spin and magnetic textures which can result. Such studies are typically focused on systems where large atomic number elements lead to strong spin–orbit coupling, in turn rendering electronic correlations weak. In contrast, here we investigate the temperature-dependent electronic structure of Ca3Ru2O7, a 4d oxide metal for which both correlations and spin–orbit coupling are pronounced and in which octahedral tilts and rotations combine to mediate both global and local inversion symmetry-breaking polar distortions. Our angle-resolved photoemission measurements reveal the destruction of a large hole-like Fermi surface upon cooling through a coupled structural and spin-reorientation transition at 48 K, accompanied by a sudden onset of quasiparticle coherence. We demonstrate how these result from band hybridization mediated by a hidden Rashba-type spin–orbit coupling. This is enabled by the bulk structural distortions and unlocked when the spin reorients perpendicular to the local symmetry-breaking potential at the Ru sites. We argue that the electronic energy gain associated with the band hybridization is actually the key driver for the phase transition, reflecting a delicate interplay between spin–orbit coupling and strong electronic correlations and revealing a route to control magnetic ordering in solids.
Markovic , I , Watson , M D , Clark , O J , Mazzola , F , Abarca Morales , E , Hooley , C , Rosner , H , Polley , C M , Balasubramanian , T , Mukherjee , S , Kikugawa , N , Sokolov , D A , Mackenzie , A & King , P D C 2020 , ' Electronically driven spin-reorientation transition of the correlated polar metal Ca 3 Ru 2 O 7 ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 117 , no. 27 , pp. 15524-15529 . https://doi.org/10.1073/pnas.2003671117
Proceedings of the National Academy of Sciences of the United States of America
Copyright © 2020 the Author(s). This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1073/pnas.2003671117
DescriptionFunding: We gratefully acknowledge support from the European Research Council (through the ERC-714193-QUESTDO project), the Royal Society, the UK Research and Innovation (via grant numbers EP/R031924/1 and EP/R025169/1), the Max-Planck Society, and the Japan Society for the Promotion of Science KAKENHI (Nos. JP17H06136 and JP18K04715) and Japan Science and Technology Agency JST-Mirai Program (No. JPMJMI18A3). IM and EAM acknowledge studentship support through the International Max-Planck Research School for the Chemistry and Physics of Quantum Materials. We thank Ulrike Nitzsche for thechnical support with the DFT calculations. We thank Diamond Light Source and Max-IV synchrotrons for access to Beamlines I05 (Proposal Nos. SI21986 and SI25040) and BLOCH (Proposal No. 20180399), respectively, that contributed to the results presented here.
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