We study transport properties of graphene with anisotropically distributed on-site impurities (adatoms) that are randomly placed on every third line drawn along carbon bonds. We show that stripe states characterized by strongly suppressed back-scattering are formed in this model in the direction of the lines. The system reveals Lévy-flight transport in stripe direction such that the corresponding conductivity increases as the square root of the system length. Thus, adding this type of disorder to clean graphene near the Dirac point strongly enhances the conductivity, which is in stark contrast with a fully random distribution of on-site impurities which leads to Anderson localization. The effect is demonstrated both by numerical simulations using the Kwant code and by an analytical theory based on the self-consistent $T$-matrix approximation.
Laser irradiation, as a versatile tool to tune topological properties of electronic systems, is under intensive studies. Experimentally, laser irradiation induced anomalous Hall effect in graphene has been observed (McIver et al., Nat. Phys. 16, 38 (2020)). Disorder is ubiquitous in real materials, and it has been shown that diagonal disorders, i.e., onsite disorder, can enhance topological properties of time-periodically driven quantum materials (Titum et al., Phys. Rev. Lett. 114, 056801 (2015)). Here, we investigate circularly polarized laser irradiated graphene with non-diagonal disorders,…
We investigate the flat phase of $D$-dimensional crystalline membranes embedded in a $d$-dimensional space and submitted to both metric and curvature quenched disorders using a nonperturbative renormalization group approach. We identify a second order phase transition controlled by a finite-temperature, finite-disorder fixed point unreachable within the leading order of $ε=4-D$ and $1/d$ expansions. This critical point divides the flow diagram into two basins of attraction: that associated to the finite-temperature fixed point controlling the long distance behaviour of disorder-free membranes …
Electron-phonon mediated heat flow in disordered graphene
我们计算的热通量和电子-声子热导在一个无序的石墨烯片,超越了费米的黄金法则的方法,充分考虑到修改的电子-声子相互作用的无序。在$k_F l >> 1$(其中$k_F$是费米波矢,l是平均自由程)体系中,采用Keldysh方法结合标准杂质平均法,我们同时考虑了电子与声子之间的标量势(即形变势)和矢量势耦合。我们还考虑了电子屏蔽的影响,在费米能级。我们发现,热通量和热导率的温度依赖性是敏感的无序和屏蔽的存在下,并反映了潜在的手性性质的电子在石墨烯和相应的修改其扩散行为。在弱屏蔽的情况下,无序增强了清洁系统的低温热通量(将相关幂律从$T^4$变为$T^3$),并且变形势占主导地位。对于强屏蔽,变形势和矢量势耦合的贡献相当,低温热流服从$T^5$幂律。
We develop a theory for a qualitatively new type of disorder in condensed matter systems arising from local twist-angle fluctuations in two strongly coupled van der Waals monolayers twisted with respect to each other to create a flat band moiré superlattice. The new paradigm of 'twist angle disorder' arises from the currently ongoing intense research activity in the physics of twisted bilayer graphene. In experimental samples of pristine twisted bilayer graphene, which are nominally free of impurities and defects, the main source of disorder is believed to arise from the unavoidable and uncont…