Nematic Crossover in ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$ under Uniaxial Stress

Nematic Crossover in ${BaFe}_{2} {As}_{2}$ under Uniaxial Stress

Xiao Ren, Lian Duan, Yuwen Hu, Jiarui Li, Rui Zhang, Huiqian Luo, Pengcheng Dai, and Yuan Li

Phys. Rev. Lett. 115, 197002 – Published 6 November 2015

Abstract

Raman scattering can detect spontaneous point-group symmetry breaking without resorting to single-domain samples. Here, we use this technique to study ${BaFe}_{2} {As}_{2}$ , the parent compound of the “122” Fe-based superconductors. We show that an applied compression along the Fe-Fe direction, which is commonly used to produce untwinned orthorhombic samples, changes the structural phase transition at temperature $T_{s}$ into a crossover that spans a considerable temperature range above $T_{s}$ . Even in crystals that are not subject to any applied force, a distribution of substantial residual stress remains, which may explain phenomena that are seemingly indicative of symmetry breaking above $T_{s}$ . Our results are consistent with an onset of spontaneous nematicity only below $T_{s}$ .

Received 8 July 2015

DOI:https://doi.org/10.1103/PhysRevLett.115.197002

Authors & Affiliations

Xiao Ren¹, Lian Duan¹, Yuwen Hu¹, Jiarui Li¹, Rui Zhang², Huiqian Luo³, Pengcheng Dai², and Yuan Li^1,4,*

¹International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
²Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
³Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
⁴Collaborative Innovation Center of Quantum Matter, Beijing 100871, China