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arXiv · 2008.06907

Strange metal behavior of the Hall angle in twisted bilayer graphene

Rui Lyu·Zachary Tuchfeld·Nishchhal Verma·Haidong Tian·Kenji Watanabe·Takashi Taniguchi·Chun Ning Lau·Mohit Randeria·Marc Bockrath
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Abstract

Twisted bilayer graphene (TBG) with interlayer twist angles near the magic angle $\approx 1.08^{\circ}$ hosts flat bands and exhibits correlated states including Mott-like insulators, superconductivity and magnetism. Here we report combined temperature-dependent transport measurements of the longitudinal and Hall resistivities in close to magic-angle TBG. While the observed longitudinal resistivity follows linear temperature $T$ dependence consistent with previous reports, the Hall resistance shows an anomalous $T$ dependence with the cotangent of the Hall angle cot $\Theta{_H} \propto T^2$. Boltzmann theory for quasiparticle transport predicts that both the resistivity and cot $\Theta{_H}$ should have the same $T$ dependence, contradicting the observed behavior. This failure of quasiparticle-based theories is reminiscent of other correlated strange metals such as cuprates.

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Rui Lyu, Zachary Tuchfeld, Nishchhal Verma, Haidong Tian, Kenji Watanabe, Takashi Taniguchi, Chun Ning Lau, Mohit Randeria, Marc Bockrath. 2020-08-16. Strange metal behavior of the Hall angle in twisted bilayer graphene. https://doi.org/10.1103/physrevb.103.245424

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