Sign-problem-free quantum Monte Carlo of the onset of antiferromagnetism in metals

TL;DR

This paper introduces sign-problem-free quantum Monte Carlo simulations for studying the onset of antiferromagnetism in metals, revealing Fermi surface changes and unconventional superconductivity near quantum critical points.

Contribution

It demonstrates a lattice model free from the sign problem that enables efficient QMC simulations of antiferromagnetic quantum criticality in metals.

Findings

Fermi surface reconstruction observed across the critical point

Unconventional spin-singlet superconductivity detected

Efficient simulation enabled by sign-problem-free lattice models

Abstract

The quantum theory of antiferromagnetism in metals is necessary for our understanding of numerous intermetallic compounds of widespread interest. In these systems, a quantum critical point emerges as external parameters (such as chemical doping) are varied. Because of the strong coupling nature of this critical point, and the "sign problem" plaguing numerical quantum Monte Carlo (QMC) methods, its theoretical understanding is still incomplete. Here, we show that the universal low-energy theory for the onset of antiferromagnetism in a metal can be realized in lattice models, which are free from the sign problem and hence can be simulated efficiently with QMC. Our simulations show Fermi surface reconstruction and unconventional spin-singlet superconductivity across the critical point.