Strange Metal in Magic-Angle Graphene with near Planckian Dissipation
Strange Metal in Magic-Angle Graphene with near Planckian Dissipation
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DOI：
10.1103/physrevlett.124.076801
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发表时间：
2020-02-18
影响因子：
8.6
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Cao, Yuan;Chowdhury, Debanjan;Jarillo-Herrero, Pablo
最近对魔角扭曲双层石墨烯的实验发现了孤立窄带部分填充时的相关绝缘行为和超导性。在这里，我们表明，对于相关绝缘体附近的一系列填充物，魔角双层石墨烯表现出强相关系统的另一个特征——在较小的密度相关交叉温度之上的广泛的 T 线性电阻率范围。这种行为让人想起其他强相关系统中的类似行为，这些系统通常被称为“奇怪的金属”，例如铜酸盐、铁磷化物、钌酸盐和钴酸盐，其中的观察结果与弱相互作用费米液体中的预期不一致。我们还提取了传输“散射率”，它满足近似普朗克形式，普遍与 (k(B)T/(h) over bar) 的比率相关。我们的研究结果将魔角双层石墨烯建立为一个高度可调的平台，用于研究奇怪的金属行为，这可以揭示这种神秘的普遍存在的相关物质相。
Recent experiments on magic-angle twisted bilayer graphene have discovered correlated insulating behavior and superconductivity at a fractional filling of an isolated narrow band. Here we show that magicangle bilayer graphene exhibits another hallmark of strongly correlated systems-a broad regime of T-linear resistivity above a small density-dependent crossover temperature-for a range of fillings near the correlated insulator. This behavior is reminiscent of similar behavior in other strongly correlated systems, often denoted "strange metals," such as cuprates, iron pnictides, ruthenates, and cobaltates, where the observations are at odds with expectations in a weakly interacting Fermi liquid. We also extract a transport "scattering rate," which satisfies a near Planckian form that is universally related to the ratio of (k(B)T/(h) over bar). Our results establish magic-angle bilayer graphene as a highly tunable platform to investigate strange metal behavior, which could shed light on this mysterious ubiquitous phase of correlated matter.