Optical anisotropy in the electronic nematic phase of FeSe

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2017-09-15
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Chinotti, Manuel
Pal, Anirban
Degiorgi, Leonardo
Canfield, Paul
Böhmer, Anna
Canfield, Paul
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Ames Laboratory
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Physics and Astronomy
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Ames LaboratoryPhysics and Astronomy
Abstract

At ambient pressure, FeSe undergoes a structural, tetragonal-to-orthorhombic, phase transition at Ts≃90 K without any magnetic ordering on further cooling. FeSe thus provides an arena for examining the nematic phase without the complications following the reconstruction of the Fermi surface due to the antiferromagnetic order within the orthorhombic state. We perform an optical-reflectivity investigation across the structural transition, as a function of uniaxial stress in order to detwin the specimen. These measurements reveal a hysteretic behavior of the anisotropic optical response to uniaxial stress for T≤Ts, which extends to energy scales of about 0.5 eV. The sign changes of the optical anisotropy between distinct energy intervals suggest a complex evolution of the polarized electronic structure in the nematic phase. The temperature dependence of the optical anisotropy for the fully detwinned specimen is furthermore acting as a proxy for the order parameter of nematicity.

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This article is published as Chinotti, Manuel, Anirban Pal, Leonardo Degiorgi, Anna E. Böhmer, and Paul C. Canfield. "Optical anisotropy in the electronic nematic phase of FeSe." Physical Review B 96, no. 12 (2017): 121112. DOI: 10.1103/PhysRevB.96.121112. Posted with permission.

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