Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Phys Rev Lett. 2015 Jan 16;114(2):027001. doi: 10.1103/PhysRevLett.114.027001. Epub 2015 Jan 15.
The nature of the tetragonal-to-orthorhombic structural transition at T_{s}≈90 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 Ba(Fe,Co){2}As{2}, suggesting a 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.
使用剪切模量、热容、磁化率和核磁共振测量研究了在 T_{s}≈90 K 附近单晶体 FeSe 中四方到正交结构相变的本质。实验表明，相变伴随着较大的剪切模量软化，这与欠掺杂 Ba(Fe,Co){2}As{2}的情况几乎完全相同，表明电子-晶格耦合的强度非常相似。另一方面，只有在 T_{s}以下才能观察到自旋-晶格弛豫率的自旋涨落贡献。这表明 FeSe 中的结构（或“向列”）相变不是由磁涨落驱动的。
