Spontaneous orbital polarization in the nematic phase of FeSe.

Autor: Occhialini CA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA., Sanchez JJ; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA., Song Q; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA., Fabbris G; Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA., Choi Y; Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA., Kim JW; Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA., Ryan PJ; Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA., Comin R; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA. rcomin@mit.edu.
Jazyk: angličtina
Zdroj: Nature materials [Nat Mater] 2023 Aug; Vol. 22 (8), pp. 985-991. Date of Electronic Publication: 2023 Jun 22.
DOI: 10.1038/s41563-023-01585-2
Abstrakt: The origin of nematicity in FeSe remains a critical outstanding question towards understanding unconventional superconductivity in proximity to nematic order. To understand what drives the nematicity, it is essential to determine which electronic degree of freedom admits a spontaneous order parameter independent from the structural distortion. Here we use X-ray linear dichroism at the Fe K pre-edge to measure the anisotropy of the 3d orbital occupation as a function of in situ applied stress and temperature across the nematic transition. Along with using X-ray diffraction to precisely quantify the strain state, we reveal a lattice-independent, spontaneously ordered orbital polarization within the nematic phase, as well as an orbital polarizability that diverges as the transition is approached from above. These results provide strong evidence that spontaneous orbital polarization serves as the primary order parameter of the nematic phase.
(© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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