• Corpus ID: 220250174

Nematic Fluctuations in an Orbital Selective Superconductor Fe$_{1+y}$Te$_{1-x}$Se$_{x}$

@article{Jiang2020NematicFI,
  title={Nematic Fluctuations in an Orbital Selective Superconductor Fe\$\_\{1+y\}\$Te\$\_\{1-x\}\$Se\$\_\{x\}\$},
  author={Qianni Jiang and Yue Shi and Morten H. Christensen and Joshua J. Sanchez and Bevin Huang and Zhong Lin and Zhaoyu Liu and Paul Malinowski and Xiaodong Xu and Rafael M. Fernandes and Jiun Haw Chu},
  journal={arXiv: Superconductivity},
  year={2020}
}

• Qianni Jiang, Yue Shi, +8 authors J. Chu
• Published 29 June 2020
• Physics
• arXiv: Superconductivity

We present a systematic study of the nematic fluctuations in the iron chalcogenide superconductor Fe$_{1+y}$Te$_{1-x}$Se$_{x}$ ($0 \leq x \leq 0.53$) using the elastoresistivity technique. Near $x = 0$, in proximity to the double-stripe magnetic order of Fe$_{1+y}$Te, a diverging $B_{1g}$ nematic susceptibility is observed. Upon increasing $x$, despite the absence of magnetic order, the $B_{2g}$ nematic susceptibility increases and becomes dominant, closely following the strength of the $(\pi, \pi)$ spin fluctuations. Over a wide range of compositions ($0.17 \leq x \leq 0.53$), while the $B_{2g}$ nematic susceptibility follows a Curie temperature dependence (with zero Weiss temperature) at low temperatures, it shows deviations from Curie-Weiss behavior for temperatures higher than $50K$. This is the opposite of what is observed in typical iron pnictides, where Curie-Weiss deviations are seen at low temperatures. We attribute this unusual temperature dependence to a loss of coherence of the $d_{xy}$ orbital, which is supported by our theoretical calculations. Our results highlight the importance of orbital differentiation on the nematic properties of iron-based materials.