论文标题
在二维中的可溶性费米子量子临界点
Soluble Fermionic Quantum Critical Point in Two Dimensions
论文作者
论文摘要
我们研究了半金属相之间两个空间维度的量子临界点的模型，其特征在于稳定的二次费米节点和一个有序相，其中频谱会形成带隙。可以精确地计算量子临界行为，我们明确地得出了各种可观察力的缩放定律。虽然临界时的订单参数相关函数满足通常的功率定律，而异常指数$ η_ϕ = 2 $，但相关长度和订单参数的期望值在接近绝缘方面的量子临界点时表现出必不可少的奇异性，类似于berezinskinskienskienskii-kosterlitz-kosterlitz-- thelestion。另一方面，敏感性具有幂律差异，非均值田指数$γ= 2 $。在半金属方面，相关长度保持无限，导致整个阶段的新出现量表不变性。
We study a model for a quantum critical point in two spatial dimensions between a semimetallic phase, characterized by a stable quadratic Fermi node, and an ordered phase, in which the spectrum develops a band gap. The quantum critical behavior can be computed exactly, and we explicitly derive the scaling laws of various observables. While the order-parameter correlation function at criticality satisfies the usual power law with anomalous exponent $η_ϕ= 2$, the correlation length and the expectation value of the order parameter exhibit essential singularities upon approaching the quantum critical point from the insulating side, akin to the Berezinskii-Kosterlitz-Thouless transition. The susceptibility, on the other hand, has a power-law divergence with non-mean-field exponent $γ= 2$. On the semimetallic side, the correlation length remains infinite, leading to an emergent scale invariance throughout this phase.
