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arXiv 1101.0216cond-mat.mes-hallcond-mat.str-el
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由外部门控制的量子线中的量子相变

Quantum phase transition in quantum wires controlled by an external gate

Tobias Meng, Mehul Dixit, Markus Garst, Julia S. Meyer

备注：
18 pages, 8 figures, minor changes, published version
发表信息：
Phys. Rev. B 83, 125323 (2011)
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摘要：

我们考虑量子线中的电子通过被附近的门屏蔽的长程库仑势相互作用。我们专注于量子相变从严格的一维到准一维电子液体，这是由无量纲参数$n x_0$，其中$n$是电子密度和$x_0$是横向限制势的特征长度控制。如果这种跃迁发生在低密度极限，它可以被理解为一维维格纳晶体变形为伊辛序参量所描述的锯齿形电子排列。的关键属性是由电荷自由度和自旋部门保持基本上解耦。在大密度，另一方面，过渡是由横向量子化的第二个一维子带的填充触发。第二子带底部的电子由于态密度的发散而强烈相互作用，并且变得不可穿透。我们认为，这稳定了电子液体，因为它抑制子带之间的对隧穿过程，否则会导致不稳定。然而，在第二带的不可穿透的电子被屏蔽的第一子带的激发，使过渡被确定为不可穿透的极化子的Lifshitz过渡。我们讨论了作为$n x_0$的函数的相图。

英文摘要：

We consider electrons in a quantum wire interacting via a long-range Coulomb potential screened by a nearby gate. We focus on the quantum phase transition from a strictly one-dimensional to a quasi-one-dimensional electron liquid, that is controlled by the dimensionless parameter $n x_0$, where $n$ is the electron density and $x_0$ is the characteristic length of the transverse confining potential. If this transition occurs in the low-density limit, it can be understood as the deformation of the one-dimensional Wigner crystal to a zigzag arrangement of the electrons described by an Ising order parameter. The critical properties are governed by the charge degrees of freedom and the spin sector remains essentially decoupled. At large densities, on the other hand, the transition is triggered by the filling of a second one-dimensional subband of transverse quantization. Electrons at the bottom of the second subband interact strongly due to the diverging density of states and become impenetrable. We argue that this stabilizes the electron liquid as it suppresses pair-tunneling processes between the subbands that would otherwise lead to an instability. However, the impenetrable electrons in the second band are screened by the excitations of the first subband, so that the transition is identified as a Lifshitz transition of impenetrable polarons. We discuss the resulting phase diagram as a function of $n x_0$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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