Inhomogeneous phase formation on the border of itinerant ferromagnetism

TL;DR

This paper demonstrates that quantum fluctuations induce an inhomogeneous magnetic phase that pre-empts the first order ferromagnetic transition near the itinerant ferromagnetism boundary, using analytical and numerical methods.

Contribution

It introduces a simplified analytical framework combined with Quantum Monte Carlo simulations to show inhomogeneous phase formation pre-empting ferromagnetic transitions.

Findings

Inhomogeneous magnetic phase forms due to quantum fluctuations.

Inhomogeneous phase pre-empts first order ferromagnetic transition.

Analytical approach simplifies previous diagrammatic methods.

Abstract

A variety of analytical techniques suggest that quantum fluctuations lead to a fundamental instability of the Fermi liquid that drives ferromagnetic transitions first order at low temperatures. We present both analytical and numerical evidence that, driven by the same quantum fluctuations, this first order transition is pre-empted by the formation of an inhomogeneous magnetic phase. This occurs in a manner that is closely analogous to the formation of the inhomogeneous superconducting Fulde-Ferrel-Larkin-Ovchinnikov state. We derive these results from a field theoretical approach supplemented with numerical Quantum Monte Carlo simulations. Our analytical approach represents a considerable simplification over diagrammatic methods, makes contact with older analyses of the unitarity limit, and enables a simple physical picture to emerge.