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arXiv · 1908.02790

Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

H. Pfau·S. D. Chen·M. Yi·M. Hashimoto·C. R. Rotundu·J. C. Palmstrom·T. Chen·P. -C. Dai·J. Straquadine·A. Hristov·R. J. Birgeneau·I. R. Fisher·D. Lu·Z. -X. Shen
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Abstract

The momentum dependence of the nematic order parameter is an important ingredient in the microscopic description of iron-based high-temperature superconductors. While recent reports on FeSe indicate that the nematic order parameter changes sign between electron and hole bands, detailed knowledge is still missing for other compounds. Combining angle-resolved photoemission spectroscopy (ARPES) with uniaxial strain tuning, we measure the nematic band splitting in both FeSe and BaFe$_2$As$_2$ without interference from either twinning or magnetic order. We find that the nematic order parameter exhibits the same momentum dependence in both compounds with a sign change between the Brillouin center and the corner. This suggests that the same microscopic mechanism drives the nematic order in spite of the very different phase diagrams.

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H. Pfau, S. D. Chen, M. Yi, M. Hashimoto, C. R. Rotundu, J. C. Palmstrom, T. Chen, P. -C. Dai, J. Straquadine, A. Hristov, R. J. Birgeneau, I. R. Fisher, D. Lu, Z. -X. Shen. 2019-08-07. Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors. https://doi.org/10.1103/physrevlett.123.066402

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