Evolution of the Andreev bands in the half-filled superconducting periodic Anderson model

TL;DR

This paper investigates how in-gap Andreev bands evolve in a half-filled superconducting periodic Anderson model, revealing two distinct superconducting phases and analyzing spectral function behavior near phase transitions.

Contribution

It introduces a detailed study of Andreev band evolution in a superconducting periodic Anderson model using advanced quantum Monte Carlo methods and phase diagram analysis.

Findings

Identification of two superconducting phases with different pairing signs

Evolution of spectral functions near phase transitions

Discussion of method limitations in superconducting models

Abstract

We employ the periodic Anderson model with superconducting correlations in the conduction band at half filling to study the behavior of the in-gap bands in a heterostructure consisting of a molecular layer deposited on the surface of a conventional superconductor. We use the dynamical mean-field theory to map the lattice model on the superconducting single impurity model with self-consistently determined bath and use the continuous-time hybridization expansion (CT-HYB) quantum Monte Carlo and the iterative perturbation theory (IPT) as solvers for the impurity problem. We present phase diagrams for square and triangular lattice that both show two superconducting phases that differ by the sign of the induced pairing, in analogy to the $0$ and $\pi$ phases of the superconducting single impurity Anderson model and discuss the evolution of the spectral function in the vicinity of the transition. We also discuss the failure of the IPT for superconducting models with spinful ground state and the behavior of the average expansion order of the CT-HYB simulation.