Pomeranchuk instability in the nematic phase of two monolayer FeSe/SrTiO3

C. Y. Tang; X. -L. Peng; Y. -H. Yuan; P. Zhang; G. -N. Phan; S. -Y. Gao; Y. -B. Huang; L. -Y. Kong; T. Qian; W. Li; Q. -K. Xue; Z. -Q. Wang; K. Jiang; Y. -J. Sun; H. Ding

arXiv · 2012.10136

Pomeranchuk instability in the nematic phase of two monolayer FeSe/SrTiO3

C. Y. Tang·X. -L. Peng·Y. -H. Yuan·P. Zhang·G. -N. Phan·S. -Y. Gao·Y. -B. Huang·L. -Y. Kong·T. Qian·W. Li·Q. -K. Xue·Z. -Q. Wang·K. Jiang·Y. -J. Sun·H. Ding

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Abstract

Nematicity, where electrons break rotational symmetry while preserving translational symmetry, is ubiquitous in strongly correlated quantum matters, including high-Tc cuprates and iron-based superconductors. A central question in nematicity is whether it is driven by Pomeranchuk instability in momentum space or orbital order (polarization) in real space, especially as nematicity intertwines with superconductivity. FeSe/SrTiO3 (STO), where nematicity occurs without long-range magnetic order, is an ideal platform for studying the nature and origin of the electronic nematicity. Here we present direct evidence of Pomeranchuk nematic order in two monolayer FeSe/STO using angle-resolved photoemission spectroscopy, revealing a remarkable degeneracy of dxz and dyz bands at the Brillouin zone center, but a significant band separation at the zone corner. This momentum-dependent nematicity demonstrates that nematicity in FeSe/STO originates from the Pomeranchuk instability, offering insights into the relationship between nematicity and superconductivity. Our results establish two-dimensional FeSe thin film as a powerful platform for investigating quantum physics under complex intertwinement.

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C. Y. Tang, X. -L. Peng, Y. -H. Yuan, P. Zhang, G. -N. Phan, S. -Y. Gao, Y. -B. Huang, L. -Y. Kong, T. Qian, W. Li, Q. -K. Xue, Z. -Q. Wang, K. Jiang, Y. -J. Sun, H. Ding. 2020-12-18. Pomeranchuk instability in the nematic phase of two monolayer FeSe/SrTiO3. https://arxiv.org/abs/2012.10136

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