Topological Mott Insulator in Three-Dimensional Systems with Quadratic Band Touching
Topological Mott Insulator in Three-Dimensional Systems with Quadratic Band Touching
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DOI：
10.1103/physrevlett.113.106401
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发表时间：
2014-09-02
影响因子：
8.6
通讯作者：
Janssen, Lukas
中科院分区：
文献类型：
--
作者：
Herbut, Igor F.;Janssen, Lukas
我们认为，在二次带接触点具有费米能级的三维电子系统，如HgTe，在任意弱远程库仑相互作用下，相对于（拓扑）莫特绝缘子的自发形成，可能是不稳定的。不稳定性的机制可以理解为Abrikosov的非费米液体不动点与另一个量子临界不动点的碰撞，该不动点在耦合空间中以系统维数d -> d(low) +接近它，“低临界维数”2 < d(low) < 4。在三维和接近二维的情况下，基于大n极限的考虑，给出了量子临界点存在的论证。在单循环计算中，我们发现d(low) = 3.26，因此在上面，但离三维不远。这转化为一个温度或能量窗口（T-c, T-*），在这个窗口上，在莫特跃迁最终发生在临界温度T-c(类似于T-* exp[- zc /(d（低）- d)(1/2)]之前，非费米液体的缩放仍然可以观察到。我们估计C = pi/1.1，动力学临界指数z近似为1.8，温标k(B)T（*）近似为(4m/m(el)epsilon(2))13.6 eV，其中m为能带质量，epsilon为介电常数。
We argue that a three-dimensional electronic system with the Fermi level at the quadratic band touching point such as HgTe could be unstable with respect to the spontaneous formation of the (topological) Mott insulator at arbitrary weak long-range Coulomb interaction. The mechanism of the instability can be understood as the collision of Abrikosov's non-Fermi liquid fixed point with another, quantum critical, fixed point, which approaches it in the coupling space as the system's dimensionality d -> d(low) +, with the "lower critical dimension" 2 < d(low) < 4. Arguments for the existence of the quantum critical point based on considerations in the large-N limit in d 3, as well as close to d 2, are given. In the one-loop calculation we find that d(low) = 3.26, and thus above, but not far from three dimensions. This translates into a temperature or energy window (T-c, T-*) over which the non-Fermi liquid scaling should still be observable, before the Mott transition finally takes place at the critical temperature T-c similar to T-* exp[-zC/(d(low) - d)(1/2)]. We estimate C = pi/1.1, dynamical critical exponent z approximate to 1.8, and the temperature scale k(B)T(*) approximate to (4m/m(el)epsilon(2))13.6 eV, with m as the band mass and epsilon as the dielectric constant.