Suppression of orbital ordering by chemical pressure in FeSe1-xSx

Journal article

We report a high-resolution angle-resolved photo-emission 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 87K to 58K 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.

Authors: Watson, MD; Kim, T; Haghighirad, A; Blake, S; Davies, N

• Publication status: Published
• Peer review status: Peer reviewed
• Journal: Physical Review B
• Volume: 92
• Issue: 12
• Pages: 121108(R)
• Publication date: 2015-08-20
• DOI: 10.1103/PhysRevB.92.121108
• EISSN: 1550-235X
• ISSN: 1098-0121
• Keywords: cond-mat.str-el; cond-mat.supr-con; cond-mat.mtrl-sci