论文标题
狄拉克流体中的非本地流体动力传输和集体激发
Non-local hydrodynamic transport and collective excitations in Dirac fluids
论文作者
论文摘要
我们研究了有限波数和流体动力状态下的频率对电场和热梯度的响应。我们发现，流体动力学状态中的非本地运输受无限的动力学模式的控制，这些模式描述了不同角度谐波通道中的非共线散射事件。这些模式的散射速率$τ_{m}^{ - 1} $随着$ \ | m \ | $的增加而增加，其中$ m $标记了角度谐波。在较早的出版物中，我们指出，这种依赖性导致异常的，莱维飞行的阶段空间扩散（Phys。Phys。Rev。Lett。123，195302（2019））。在这里，我们展示了这种令人惊讶的简单，非分析依赖性如何使我们获得非本地电荷和电子导电性的精确表达式。散射速率对$ m $的特殊依赖性也导致了集体激发的非平凡结构：除了众所周知的等离子体，第二种声音和扩散模式外，我们发现非脱位的阻尼模式对应于较高角度谐波的激发。我们使用这些结果来研究狄拉克流体通过不同宽度的Poiseuille型几何形状的传输，并研究石墨烯 - pizoelectric设备中对表面声波的响应。
We study the response of a Dirac fluid to electric fields and thermal gradients at finite wave-numbers and frequencies in the hydrodynamic regime. We find that non-local transport in the hydrodynamic regime is governed by infinite set of kinetic modes that describe non-collinear scattering events in different angular harmonic channels. The scattering rates of these modes $τ_{m}^{-1}$ increase as $\|m\|$, where $m$ labels the angular harmonics. In an earlier publication, we pointed out that this dependence leads to anomalous, Lévy-flight-like phase space diffusion (Phys. Rev. Lett. 123, 195302 (2019)). Here, we show how this surprisingly simple, non-analytic dependence allows us to obtain exact expressions for the non-local charge and electronic thermal conductivities. The peculiar dependence of the scattering rates on $m$ also leads to a non-trivial structure of collective excitations: Besides the well known plasmon, second sound and diffusive modes, we find non-degenerate damped modes corresponding to excitations of higher angular harmonics. We use these results to investigate the transport of a Dirac fluid through Poiseuille-type geometries of different widths, and to study the response to surface acoustic waves in graphene-piezoelectric devices.
