Pair-density-wave superconductivity: a microscopic model on 2D honeycomb lattice

TL;DR

This paper presents a microscopic model on a 2D honeycomb lattice demonstrating the existence of pair-density-wave superconductivity, supported by advanced numerical simulations showing long-range PDW order in the ground state.

Contribution

It provides the first controlled numerical evidence of PDW order in a 2D-like Fermi surface system using DMRG on a minimal spinless fermion model.

Findings

PDW order observed in the ground state of the model.

PDW state persists on wider cylinders with 2D-like Fermi surfaces.

First numerical evidence of PDW in systems with 2D-like Fermi surfaces.

Abstract

Pair-density-wave (PDW) is a long-sought exotic state with oscillating superconducting order without external magnetic field. So far it has been rare in establishing a 2D microscopic model with PDW long-range order in its ground state. Here we propose to study PDW superconductivity in a minimal model of spinless fermions on the honeycomb lattice with nearest-neighbor (NN) and next-nearest-neighbor (NNN) interaction $V_1$ and $V_2$, respectively. By performing a state-of-the-art density-matrix renormalization group (DMRG) study of this $t$-$V_1$-$V_2$ model at finite doping on six-leg and eight-leg honeycomb cylinders, we showed that the ground state exhibits PDW ordering (namely quasi-long-range order with a divergent PDW susceptibility). Remarkably this PDW state persists on the wider cylinder with 2D-like Fermi surfaces (FS). To the best of our knowledge, this is probably the first controlled numerical evidence of PDW in systems with 2D-like FS.