Doron A, Tamir I, Levinson T, Ovadia M, Sacépé B, Shahar D
Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel.
Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France.
Phys Rev Lett. 2017 Dec 15;119(24):247001. doi: 10.1103/PhysRevLett.119.247001. Epub 2017 Dec 13.
Thin films of amorphous indium oxide undergo a magnetic field driven superconducting to insulator quantum phase transition. In the insulating phase, the current-voltage characteristics show large current discontinuities due to overheating of electrons. We show that the onset voltage for the discontinuities vanishes as we approach the quantum critical point. As a result, the insulating phase becomes unstable with respect to any applied voltage making it, at least experimentally, immeasurable. We emphasize that unlike previous reports of the absence of linear response near quantum phase transitions, in our system, the departure from equilibrium is discontinuous. Because the conditions for these discontinuities are satisfied in most insulators at low temperatures, and due to the decay of all characteristic energy scales near quantum phase transitions, we believe that this instability is general and should occur in various systems while approaching their quantum critical point. Accounting for this instability is crucial for determining the critical behavior of systems near the transition.
非晶态氧化铟薄膜会经历磁场驱动的超导到绝缘体的量子相变。在绝缘相中，由于电子过热，电流 - 电压特性呈现出较大的电流间断。我们表明，当接近量子临界点时，这些间断的起始电压会消失。结果，绝缘相对于任何施加电压都变得不稳定，这使得至少在实验上它变得无法测量。我们强调，与之前关于量子相变附近不存在线性响应的报道不同，在我们的系统中，偏离平衡是不连续的。由于这些间断的条件在大多数低温绝缘体中都能满足，并且由于量子相变附近所有特征能量尺度的衰减，我们认为这种不稳定性是普遍存在的，并且在各种系统接近其量子临界点时都应该会发生。考虑这种不稳定性对于确定接近转变的系统的临界行为至关重要。
