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Suppression of orbital ordering by chemical pressure in FeSe 1−x S x

DOI: 10.1103/PhysRevB.92.121108 DOI Help

Authors: M. D. Watson (Clarendon Laboratory, Department of Physics, University of Oxford) , T. Kim (Diamond Light Source) , A. A. Haghighirad (University of Oxford) , S Blake (University of Oxford) , N. R. Davies (University of Oxford) , M Hoesch (Diamond Light Source) , T. Wolf (Karlsruhe Institute of Technology) , A. I Coldea (Clarendon Laboratory, Department of Physics, University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 92 (12)

State: Published (Approved)
Published: September 2015
Diamond Proposal Number(s): 11792

Abstract: We report a high-resolution angle-resolved photoemission spectroscopy study of the evolution of the electronic structure of FeSe1−xSx single crystals. Isovalent S substitution onto the Se site constitutes a chemical pressure which subtly modifies the electronic structure of FeSe at high temperatures and induces a suppression of the tetragonal-symmetry-breaking structural transition temperature from 87 to 58 K for x=0.15. With increasing S substitution, we find smaller splitting between bands with dyz and dxz orbital character and weaker anisotropic distortions of the low-temperature Fermi surfaces. These effects evolve systematically as a function of both S substitution and temperature, providing strong evidence that an orbital ordering is the underlying order parameter of the structural transition in FeSe1−xSx. Finally, we detect the small inner hole pocket for x=0.12, which is pushed below the Fermi level in the orbitally ordered low-temperature Fermi surface of FeSe.

Journal Keywords: Arpes; Superconductivity; Fese

Subject Areas: Physics, Materials

Instruments: I05-ARPES