Collapse of Critical Nematic Fluctuations in FeSe under Pressure
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.
- Publication:
-
Physical Review Letters
- Pub Date:
- August 2018
- DOI:
- 10.1103/PhysRevLett.121.077001
- arXiv:
- arXiv:1801.10316
- Bibcode:
- 2018PhRvL.121g7001M
- Keywords:
-
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 7 pages, 4 figures. Supplementary Material available upon request