Collapse of Critical Nematic Fluctuations in FeSe under Pressure

Pierre Massat, Yundi Quan, Romain Grasset, Marie-Aude Méasson, Maximilien Cazayous, Alain Sacuto, Sandra Karlsson, Pierre Strobel, Pierre Toulemonde, Zhiping Yin, and Yann Gallais
Phys. Rev. Lett. 121, 077001 – Published 14 August 2018
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Abstract

We report the evolution of the electronic nematic susceptibility in FeSe via Raman scattering as a function of hydrostatic pressure up to 5.8 GPa where the superconducting transition temperature Tc reaches its maximum. The critical nematic fluctuations observed at low pressure vanish above 1.6 GPa, indicating they play a marginal role in the fourfold enhancement of Tc at higher pressures. The collapse of nematic fluctuations appears to be linked to a suppression of low energy electronic excitations which manifests itself by optical phonon anomalies at around 2 GPa, in agreement with lattice dynamical and electronic structure calculations using local density approximation combined with dynamical mean field theory. Our results reveal two different regimes of nematicity in the phase diagram of FeSe under pressure: a d-wave Pomeranchuk instability of the Fermi surface at low pressure and a magnetic driven orthorhombic distortion at higher pressure.

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  • Received 30 January 2018
  • Revised 28 May 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.077001

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Pierre Massat1,*, Yundi Quan2, Romain Grasset1, Marie-Aude Méasson1,3, Maximilien Cazayous1, Alain Sacuto1, Sandra Karlsson3,†, Pierre Strobel3, Pierre Toulemonde3, Zhiping Yin2,‡, and Yann Gallais1,§

  • 1Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot, Paris, France
  • 2Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875, China
  • 3Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, F-38000 Grenoble, France

  • *pierre.massat@paris7.jussieu.fr
  • Present address: Department of Quantum Matter, Physics University of Geneva, 24 Quai Ernest-Ansermet—1211 Geneva 4, Switzerland.
  • yinzhiping@bnu.edu.cn
  • §yann.gallais@paris7.jussieu.fr

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Issue

Vol. 121, Iss. 7 — 17 August 2018

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