Zero temperature superconductor - edge metal - insulator transition in $2D$ bosonic systems

Abstract

Motivated by the recent experimental observation of an intermediate bosonic metallic state in the two-dimensional superconductor-insulator transition at $T=0$, we study an extended Bose Hubbard model in the limit of large number of particles per site. Using a representation of this in terms of two coupled $XY$ models, we find, in addition to an insulating phase and a $(2+1)D$ superfluid phase, two other phases. One phase is a $2D$ superfluid phase where a crossover from $(2+1)D$ to $2D$ has taken place as a result of incipient charge ordering, signaled by $\theta$ disordering, and which is closely related to a supersolid phase. The other new phase is an edge metal state characterized by zero superfluid stiffness, zero charge ordering, and zero bulk compressibility. However, the edge compressibility of the system is nonzero. While we do not find any intermediate state with $2D$ metallic conductivity, we are able to connect these results to STM experiments on $\mathrm{Mo}{\mathrm{S}}_2$ showing brims of finite density of states around the entire edge of $2D$ $\mathrm{Mo}{\mathrm{S}}_2$ samples.

References in corpus (7)

• Magnetically Induced Metallic Phase in Superconducting Tantalum Films
• Particle-hole symmetry reveals failed superconductivity in the metallic phase of two-dimensional superconducting films
• Local Quantum Criticality in the Two-dimensional Dissipative Quantum XY Model
• Superfluid transition and specific heat of the 2D x-y model: Monte Carlo simulation
• Floating phase in a dissipative Josephson junction array
• Three distinct types of quantum phase transitions in a (2+1)-dimensional array of dissipative Josephson junctions
• Disorder-induced superconductor to insulator transition and finite phase stiffness in two-dimensional phase-glass models