论文标题
扭曲双层石墨烯中热电学的半经典描述过多的熵和分解，接近一半填充
Excess entropy and breakdown of semiclassical description of thermoelectricity in twisted bilayer graphene close to half filling
论文作者
论文摘要
在具有扭曲双层石墨烯（TBLG）的Moiré系统中，低扭转角（$θ$）的库仑相关效应的扩增是van Hove单数（VHS）几乎平坦的低能电子带和状态（DOS）的不同状态（DOS）的结果。这不仅会引起超导性，莫特绝缘状态和量子异常的霍尔效应，接近临界（或魔术）角度$θ=θ_{c} \大约1.1^\ circ $，而且非常规金属状态，这些状态被认为表现出非纤维化液体（NFL）兴奋。但是，与DOS中的超导性和相关诱导的间隙不同，金属状态中NFL效应的明确特征在实验上仍然难以捉摸。在这里，我们报告了电阻率（$ρ$）和TBLG中的热电功率（$ s $）的同时测量$θ\大约1.6^\ Circ $。我们观察到紧急违反了半经典的Mott关系，其形式接近半填充。多余的$ s $（$ \ \ \ 2 $ $ $ $ $ v/k在低温下$ t \ sim 10 $ k）持续至$ \ \ \ \ $ \ $ \约40 $ k，并伴随着金属$ t $ -linear $ρ$，其运输散射率（$τ^{ - 1} $）接近$ c}非平凡的电运输和违反Mott关系的结合提供了令人信服的NFL物理学固有的固有的，以小扭曲角度和半填充。
In moiré systems with twisted bilayer graphene (tBLG), the amplification of Coulomb correlation effects at low twist angles ($θ$) is a result of nearly flat low-energy electronic bands and divergent density of states (DOS) at van Hove singularities (vHS). This not only causes superconductivity, Mott insulating states, and quantum anomalous Hall effect close to the critical (or magic) angle $θ= θ_{c} \approx 1.1^\circ$, but also unconventional metallic states that are claimed to exhibit non-Fermi liquid (NFL) excitations. However, unlike superconductivity and the correlation-induced gap in the DOS, unambiguous signatures of NFL effects in the metallic state remain experimentally elusive. Here we report simultaneous measurement of electrical resistivity ($ρ$) and thermoelectric power ($S$) in tBLG at $θ\approx 1.6^\circ$. We observe an emergent violation of the semiclassical Mott relation in the form of excess $S$ close to half-filling. The excess $S$ ($\approx 2$ $μ$V/K at low temperature $T \sim 10$ K) persists up to $\approx 40$ K, and is accompanied by metallic $T$-linear $ρ$ with transport scattering rate ($τ^{-1}$) of near-Planckian magnitude $τ^{-1} \sim k_{B}T/\hbar$. The combination of non-trivial electrical transport and violation of Mott relation provides compelling evidence of NFL physics intrinsic to tBLG, at small twist angle and half-filling.
