Origin of the Tetragonal-to-Orthorhombic Phase Transition in FeSe: A Combined Thermodynamic and NMR Study of Nematicity
Origin of the Tetragonal-to-Orthorhombic Phase Transition in FeSe: A Combined Thermodynamic and NMR Study of Nematicity
The nature of the tetragonal-to-orthorhombic structural transition at ${T}_{s}\ensuremath{\approx}90\text{ }\text{ }\mathrm{K}$ in single crystalline FeSe is studied using shear-modulus, heat-capacity, magnetization, and nuclear magnetic resonance measurements. The transition is shown to be accompanied by a large shear-modulus softening, which is practically identical to that of underdoped $\mathrm{Ba}(\mathrm{Fe},\mathrm{Co}{)}_{2}{\mathrm{As}}_{2}$, suggesting a very …