Metal-Insulator Transition and Emergent Gapped Phase in the Surface-Doped 2D Semiconductor 2H-MoTe$_2$

Edge quantum criticality and emergent supersymmetry in topological phases

Proposed as a fundamental symmetry describing our universe, spacetime supersymmetry (SUSY) has not been discovered yet in nature. Nonetheless, it has been predicted that SUSY may emerge in low-energy physics of quantum materials such as topological superconductors and Weyl semimetals. Here, by performing state-of-the-art sign-problem-free Majorana quantum Monte Carlo (QMC) simulations of an interacting 2D topological superconductor, we show convincing evidences that the N=1 SUSY emerges at its edge quantum critical point (EQCP) while its bulk remains gapped and topologically nontrivial. Remark…

Coulomb-induced instabilities of nodal surfaces

We consider the stability of nodal surfaces in fermionic band systems with respect to the Coulomb repulsion. It is shown that nodal surfaces at the Fermi level are gapped out at low temperatures due to emergent particle-hole orders. Energy dispersion of the nodal surface suppresses the instability through an inhomogenous phase. We argue that around criticality the order parameter fluctuations can induce superconductivity. We show that by tuning doping and disorder one could access various phases, establishing fermionic nodal surface systems as a versatile platform to study emergent quantum ord…

阿布里科索夫涡旋晶格中拓扑保护的涌现费米面

Topologically protected emergent Fermi surface in an Abrikosov vortex lattice

我们证明第二类超导体中阿布里科索夫涡旋晶格可涌现出由Z2拓扑指标保护的CdGM准粒子费米面，并确认其存在于超导狄拉克半金属及掺杂绝缘体等体系中。

Holographic unitary renormalization group for correlated electrons -- II: insights on fermionic criticality

Capturing the interplay between electronic correlations and many-particle entanglement requires a unified framework for Hamiltonian and eigenbasis renormalization. In this work, we apply the unitary renormalization group (URG) scheme developed in a companion work (Ref.[1]) to the study of two archetypal models of stongly correlated lattice electrons, one with translation invariance and one without. We obtain detailed insight into the emergence of various gapless and gapped phases of quantum electronic matter by computing effective Hamiltonians as well as entanglement signatures through their r…

Non-Abelian Majorana modes protected by an emergent second Chern number

The search for topological superconductors and non-Abelian Majorana modes ranks among the most fascinating topics in condensed matter physics. There now exist several fundamental superconducting phases which host symmetry protected or chiral Majorana modes. The latter, namely the chiral Majorana modes are protected by Chern numbers in even dimensions. Here we propose to observe novel chiral Majorana modes by realizing Fulde-Ferrell-Larkin-Ovchinnikov state, i.e. the pairing density wave (PDW) phase in a Weyl semimetal which breaks time-reversal symmetry. Without symmetry protection, the 3D gap…

Emergent CPT violation from the splitting of Fermi points

In a fermionic quantum vacuum, the parameters k_μof a CPT-violating Chern-Simons-like action term induced by CPT-violating parameters of the fermionic sector depend on the universality class of the system. As a concrete example, we consider the Dirac Hamiltonian of a massive fermionic quasiparticle and add a particular term with purely-spacelike CPT-violating parameters b_μ=(0,{\bf b}). A quantum phase transition separates two phases, one with a fully-gapped fermion spectrum and the other with topologically-protected Fermi points (gap nodes). The emergent Chern-Simons ``vector'' k_μ=(0,{\bf k}…

Universality of pseudogap and emergent order in lightly doped Mott insulators

It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators. The physics of the parent state seems deceivingly simple: The hopping of the electrons from site to site is prohibited because their on-site Coulomb repulsion U is larger than the kinetic energy gain t. When doping these materials by inserting a small percentage of extra carriers, the electrons become mobile but the strong correlations from the Mott state are thought to survive; inhomogeneous electronic order, a mysterious pseudogap and, eventually, superconductivity appear. How th…

非传统超导性在重新进入和分数量子反常霍尔绝缘体附近的特征

Signatures of unconventional superconductivity near reentrant and fractional quantum anomalous Hall insulators

研究在扭曲双层MoTe₂的首个莫尔陈带中观察到整数和分数量子反常霍尔效应、重新进入量子反常霍尔效应和超导性，揭示了在同时包含分数量子反常效应的平坦陈带中出现超导性的首次实例。