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Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7

DOI: 10.1073/pnas.2003671117 DOI Help

Authors: Igor Markovic (University of St Andrews; Max Planck Institute for Chemical Physics of Solids) , Matthew D. Watson (Diamond Light Source) , Oliver J. Clark (University of St Andrews) , Federico Mazzola (University of St Andrews) , Edgar Abarca Morales (University of St Andrews; Max Planck Institute for Chemical Physics of Solids) , Chris A. Hooley (University of St Andrews) , Helge Rosner (Max Planck Institute for Chemical Physics of Solids) , Craig M. Polley (Lund University) , Thiagarajan Balasubramanian (Lund University) , Saumya Mukherjee (Diamond Light Source) , Naoki Kikugawa (National Institute for Materials Science, Japan) , Dmitry A. Sokolov (Max Planck Institute for Chemical Physics of Solids) , Andrew P. Mackenzie (University of St Andrews) , Phil D. C. King (Max Planck Institute for Chemical Physics of Solids)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Proceedings Of The National Academy Of Sciences , VOL vol. 105

State: Published (Approved)
Published: June 2020
Diamond Proposal Number(s): 21986 , 25040

Abstract: 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.

Journal Keywords: ruthenate; magnetism; correlated oxide; Rashba spin–orbit; angle-resolved photoemission

Subject Areas: Physics, Materials

Instruments: I05-ARPES

Other Facilities: Bloch beamline at MAX IV