Corbino增强的GaAs二维电子系统中的超音速声发射阈值
Corbino-Enhanced Supersonic Acoustic-Emission Threshold in a GaAs Two-Dimensional Electron System
- Instituto de Física da Universidade de São Paulo（圣保罗大学物理研究所）
- Institute of Semiconductor Physics（半导体物理研究所）
- Novosibirsk State University（新西伯利亚国立大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究在Corbino几何的GaAs二维电子系统中发现极性选择性的微分电阻阈值峰，归因于径向电流集中导致的切伦科夫类超音速声子发射，为探测局部非平衡电子-声子过程提供了灵敏平台。
AI中文摘要：
我们报告了在Corbino几何结构中图案化的高迁移率GaAs/AlGaAs二维电子系统中的非线性微分电阻测量。在零磁场下，$R_{\mathrm{diff}}(I_{dc})$在负电流分支上表现出明显的极性选择性阈值峰，该峰被垂直磁场逐渐抑制。我们将Corbino异常解释为声学声子发射的局部切伦科夫类阈值，该阈值由径向电流集中$j_r(r)=I/(2\pi r)$实现，使得局部电子速度在内接触附近的区域内超过声速。极性选择性归因于Peltier加热和冷却，它们改变了接触附近的局部热和边界条件，而非运动学阈值本身。我们的结果确定了Corbino几何结构作为在高迁移率电子系统中探测局部非平衡电子-声子过程的灵敏平台，该系统处于独立建立的流体动力学交叉区域，并表明内Corbino接触可以充当几何定义的超音速声发射源。
英文摘要：
We report nonlinear differential-resistance measurements in a high-mobility GaAs/AlGaAs two-dimensional electron system patterned in a Corbino geometry. At zero magnetic field, $R_{\mathrm{diff}}(I_{dc})$ exhibits a pronounced polarity-selective threshold peak on the negative-current branch, gradually suppressed by a perpendicular magnetic field. We interpret the Corbino anomaly as a local Cherenkov-like threshold for acoustic phonon emission, enabled by the radial current concentration $j_r(r)=I/(2πr)$, which drives the local electron velocity above the sound velocity in a region adjacent to the inner contact. The polarity selectivity is attributed to Peltier heating and cooling, which modify the local thermal and boundary conditions near the contact, rather than to the kinematic threshold itself. Our results identify the Corbino geometry as a sensitive platform for probing local nonequilibrium electron--phonon processes in a high-mobility electron system within an independently established hydrodynamic-crossover regime and suggest that the inner Corbino contact can act as a geometry-defined source for supersonic acoustic emission.
