Nematicity and Competing Orders in Superconducting Magic-Angle Graphene

Yuan Cao; Daniel Rodan-Legrain; Jeong Min Park; Fanqi Noah Yuan; Kenji Watanabe; Takashi Taniguchi; Rafael M. Fernandes; Liang Fu; Pablo Jarillo-Herrero

doi:10.1126/science.abc2836

arXiv · 2004.04148

Nematicity and Competing Orders in Superconducting Magic-Angle Graphene

Yuan Cao·Daniel Rodan-Legrain·Jeong Min Park·Fanqi Noah Yuan·Kenji Watanabe·Takashi Taniguchi·Rafael M. Fernandes·Liang Fu·Pablo Jarillo-Herrero

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Abstract

Strongly interacting electrons in solid-state systems often display tendency towards multiple broken symmetries in the ground state. The complex interplay between different order parameters can give rise to a rich phase diagram. Here, we report on the identification of intertwined phases with broken rotational symmetry in magic-angle twisted bilayer graphene (TBG). Using transverse resistance measurements, we find a strongly anisotropic phase located in a 'wedge' above the underdoped region of the superconducting dome. Upon crossing the superconducting dome, a reduction of the critical temperature is observed, similar to the behavior of certain cuprate superconductors. Furthermore, the superconducting state exhibits a anisotropic response to an directional-dependent in-plane magnetic field, revealing a nematic pairing state across the entire superconducting dome. These results indicate that nematic fluctuations might play an important role in the low-temperature phases of magic-angle TBG, and pave the way for using highly-tunable moir\'{e} superlattices to investigate intertwined phases in quantum materials.

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Yuan Cao, Daniel Rodan-Legrain, Jeong Min Park, Fanqi Noah Yuan, Kenji Watanabe, Takashi Taniguchi, Rafael M. Fernandes, Liang Fu, Pablo Jarillo-Herrero. 2020-04-08. Nematicity and Competing Orders in Superconducting Magic-Angle Graphene. https://doi.org/10.1126/science.abc2836

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