Altermagnetic pseudogap from $\frac{t}{U}$ expansion

TL;DR

This paper identifies a new altermagnetic phase in doped Mott insulators using a t/U expansion, revealing its role in the pseudogap region and its potential to lead to exotic quantum states.

Contribution

It introduces the concept of an altermagnetic pseudogap phase driven by kinetic interactions, bridging antiferromagnetism and superconductivity in doped Mott insulators.

Findings

Altermagnet occupies a region between antiferromagnet and d-wave superconductor.

The altermagnet boundary influences the phase diagram, resembling the pseudogap crossover.

Leading instability towards a $\pi$-flux state suggests emergence of spin-charge liquids.

Abstract

Order parameter analysis of the t/U series reveals a uniform altermagnet endemic to the doped Mott insulator, driven by kinetic interactions, occupying a position between the antiferromagnet and hole-doped d-wave superconductor that is normally reserved for the pseudogap. The metastable boundary of the altermagnet punctures and divides the superconductor into underdoped and overdoped regions, reminiscent of the $T^\ast$ crossover or transition in the cuprates. Similarly, the $T_{pair}$ boundary of the superconductor divides the altermagnet, leading to a low temperature phase susceptible to Cooper fluctuations. The altermagnet is unstable to inhomegeneous spin and charge order of sites, bonds, and currents. Its leading instability is to the $\pi$-flux state, suggesting the possible emergence of spin-charge liquids and quantum ordered states from a physically realistic microscopic model.