Competing Orders in a Nearly Antiferromagnetic Metal

TL;DR

This study uses quantum Monte Carlo simulations to explore the interplay of spin-density wave order and superconductivity in a model of itinerant electrons, revealing a dome-shaped d-wave superconducting phase and fluctuation effects near a magnetic quantum critical point.

Contribution

It provides a numerically exact analysis of competing orders in a two-dimensional lattice model, elucidating the microscopic mechanisms behind unconventional superconductivity.

Findings

Dome-shaped d-wave superconducting phase near magnetic quantum critical point

Extended fluctuation regime with a gap in the density of states and enhanced diamagnetism

Charge density wave fluctuations remain short-ranged near the transition

Abstract

We study the onset of spin-density wave order in itinerant electron systems via a two-dimensional lattice model amenable to numerically exact, sign-problem-free determinantal quantum Monte Carlo simulations. The finite-temperature phase diagram of the model reveals a dome-shaped $d$-wave superconducting phase near the magnetic quantum phase transition. Above the critical superconducting temperature, we observe an extended fluctuation regime, which manifests itself in the opening of a gap in the electronic density of states and an enhanced diamagnetic response. While charge density wave fluctuations are moderately enhanced in the proximity of the magnetic quantum phase transition, they remain short-ranged. The striking similarity of our results to the phenomenology of many unconventional superconductors points a way to a microscopic understanding of such strongly coupled systems in a controlled manner.