Nematic quantum criticality in three-dimensional Fermi system with quadratic band touching
Nematic quantum criticality in three-dimensional Fermi system with quadratic band touching
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DOI：
10.1103/physrevb.92.045117
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发表时间：
2015-07-20
影响因子：
3.7
通讯作者：
Herbut, Igor F.
中科院分区：
文献类型：
--
作者：
Janssen, Lukas;Herbut, Igor F.
构造并讨论了三维空间中二次带接触点处张量序参量与无带隙四分量费米子耦合的场论。在一个适当的ε-展开式中，这个理论被发现有一个量子临界点，它描述了从半金属到莫特绝缘体的（可能是连续的）转变。后一个阶段打破了旋转，但不是时间反演，对称性，并可能与材料，如灰锡或碲化汞在低温下。临界点代表了一个简单的量子模拟熟悉的经典各向同性到液晶的转变。这个量子临界点的性质和后果进行了讨论。它的存在支持了“定点碰撞”的假设，根据这种假设，具有二次带接触和长程库仑相互作用的三维费米系统在低温下对带隙基态是不稳定的。
We construct and discuss the field theory for tensorial nematic order parameter coupled to gapless four-component fermions at the quadratic band touching point in three (spatial) dimensions. Within a properly formulated epsilon-expansion this theory is found to have a quantum critical point, which describes the (presumably continuous) transition from the semimetal into a (nematic) Mott insulator. The latter phase breaks the rotational, but not the time-reversal, symmetry and may be relevant to materials such as gray tin or mercury telluride at low temperatures. The critical point represents a simple quantum analog of the familiar classical isotropic-to-nematic transition in liquid crystals. The properties and the consequences of this quantum critical point are discussed. Its existence supports the scenario of the "fixed-point collision," according to which three-dimensional Fermi systems with quadratic band touching and long-range Coulomb interactions are unstable towards the gapped nematic ground state at low temperatures.