Strange metal behavior of the Hall angle in twisted bilayer graphene

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.

References in corpus (3)

• Boron nitride substrates for high-quality graphene electronics
• Fermi-liquid instabilities at magnetic quantum phase transitions
• Continuum Model of the Twisted Bilayer

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• Robust $T$-Linear Resistivity due to SU(4) Valley + Spin Fluctuation Mechanism in Magic Angle Twisted Bilayer Graphene
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