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arXiv · 1407.5497

Origin of the tetragonal-to-orthorhombic (nematic) phase transition in FeSe: a combined thermodynamic and NMR study

A. E. Böhmer·T. Arai·F. Hardy·T. Hattori·T. Iye·T. Wolf·H. v. Löhneysen·K. Ishida·C. Meingast
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Abstract

The nature of the tetragonal-to-orthorhombic structural transition at $T_s\approx90$ K in single crystalline FeSe is studied using shear-modulus, heat-capacity, magnetization and NMR measurements. The transition is shown to be accompanied by a large shear-modulus softening, which is practically identical to that of underdoped Ba(Fe,Co)$_2$As$_2$, suggesting very similar strength of the electron-lattice coupling. On the other hand, a spin-fluctuation contribution to the spin-lattice relaxation rate is only observed below $T_s$. This indicates that the structural, or "nematic", phase transition in FeSe is not driven by magnetic fluctuations.

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A. E. Böhmer, T. Arai, F. Hardy, T. Hattori, T. Iye, T. Wolf, H. v. Löhneysen, K. Ishida, C. Meingast. 2014-07-21. Origin of the tetragonal-to-orthorhombic (nematic) phase transition in FeSe: a combined thermodynamic and NMR study. https://doi.org/10.1103/physrevlett.114.027001

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