Hydrodynamic instabilities driven by a direct current are analyzed in 2D and 3D relativisticlike systems with the Dyakonov-Shur boundary conditions supplemented by a boundary condition for temperature. Besides the conventional Dyakonov-Shur instability for plasmons, we find an entropy wave instability in both 2D and 3D systems. The entropy wave instability is a manifestation of the relativisticlike nature of electron quasiparticles and a nontrivial role of the energy current in such systems. These two instabilities occur for the opposite directions of fluid flow. While the Dyakonov-Shur instability is characterized by the plasma frequency in 3D and the system size in 2D, the frequency of the entropy wave instability is tunable by the system size and the flow velocity.

中文翻译：

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狄拉克和外尔半金属中的熵波不稳定性

在 2D 和 3D 类相对论系统中分析由直流驱动的流体动力学不稳定性，其中 Dyakonov-Shur 边界条件辅以温度边界条件。除了等离子体的传统 Dyakonov-Shur 不稳定性之外，我们还发现了 2D 和 3D 系统中的熵波不稳定性。熵波不稳定性是电子准粒子的类相对论性质和能流在此类系统中的重要作用的表现。这两种不稳定性发生在相反的流体流动方向上。虽然 Dyakonov-Shur 不稳定性的特征在于 3D 中的等离子体频率和 2D 中的系统尺寸，但熵波不稳定性的频率可通过系统尺寸和流速进行调节。