Competing nodal d-wave superconductivity and antiferromagnetism

TL;DR

This study uses unbiased Quantum Monte Carlo simulations on a sign-problem-free model to explore the phase diagram of competing d-wave superconductivity and antiferromagnetism, revealing three distinct phases and their critical transitions.

Contribution

It introduces a sign-problem-free toy model that captures the competition between d-wave superconductivity and antiferromagnetism, with detailed analysis of phase transitions.

Findings

Identification of three phases: nodal d-wave, antiferromagnet, and coexistence phase.

Characterization of phase transitions: XY universality class and Heisenberg-Gross-Neveu theory.

Phase diagram topology resembles layered organic materials with pressure-tuned Mott transition.

Abstract

Competing unconventional superconductivity and antiferromagnetism widely exist in several strongly correlated quantum materials whose direct simulation generally suffers from fermion sign problem. Here we report unbiased Quantum Monte Carlo (QMC) simulations on a sign-problem-free repulsive toy model with same onsite symmetries as the standard Hubbard model on a 2D square lattice. Using QMC, supplemented with mean-field and continuum field-theory arguments, we find that it hosts three distinct phases: a nodal d-wave phase, an antiferromagnet, and an intervening phase which hosts coexisting antiferromagnetism and nodeless d-wave superconductivity. The transition from the coexisting phase to the antiferromagnet is described by the 2+1-D XY universality class, while the one from the coexisting phase to the nodal d-wave phase is described by the Heisenberg-Gross-Neveu theory. The topology of our phase diagram resembles that of layered organic materials which host pressure tuned Mott transition from antiferromagnet to unconventional superconductor at half-filling.