The antiferromagnetic phase of the Floquet-driven Hubbard model

TL;DR

This paper investigates how periodic driving affects the antiferromagnetic phase in the Hubbard model, revealing non-thermal magnon distributions and phase destruction at high drive amplitudes.

Contribution

It provides a saddle point plus fluctuations analysis of the driven Hubbard model, highlighting non-equilibrium effects and phase transitions induced by external driving.

Findings

Discontinuous transitions to time-dependent solutions below the equilibrium gap

Non-thermal magnon distributions at high drive frequencies

Antiferromagnetism is destroyed at high drive amplitudes and low frequencies

Abstract

A saddle point plus fluctuations analysis of the periodically driven half-filled two-dimensional Hubbard model is performed. For drive frequencies below the equilibrium gap, we find discontinuous transitions to time-dependent solutions. A highly excited, generically non-thermal distribution of magnons occurs even for drive frequencies far above the gap. Above a critical drive amplitude, the low-energy magnon distribution diverges as the frequency tends to zero and antiferromagnetism is destroyed, revealing the generic importance of collective mode excitations arising from a non-equilibrium drive.