Altermagnetism on the Shastry-Sutherland lattice

TL;DR

This paper explores altermagnetism in the Hubbard model on the Shastry-Sutherland lattice, revealing non-relativistic Zeeman splitting without net magnetization, using advanced Monte Carlo methods to analyze ground states and spectral functions.

Contribution

It demonstrates the emergence of d-wave altermagnetism in a strongly correlated system and characterizes its phases and spectral properties beyond single-particle approximations.

Findings

Altermagnetic phase exhibits spin-split electronic excitations.

Metal-insulator transition characterized in the altermagnetic regime.

Altermagnetism persists across doping levels and in Mott insulators.

Abstract

Motivated by recent developments on altermagnetism, we investigate the Hubbard model on the Shastry-Sutherland lattice, where the onsite repulsion between electrons induces the onset of a staggered magnetic order in which opposite magnetic sublattices are related to each other only by rotations and glide reflections, and not by inversion nor translations. As a consequence, the magnetic phase displays an altermagnetic character, i.e. a finite (non-relativistic) Zeeman splitting of the electronic excitations, despite the absence of a net magnetization. By means of a variational Monte Carlo approach based on Jastrow-Slater wave functions, which accounts for electronic correlations beyond the single-particle approximation, we study how $d$-wave altermagnetism shows up in the ground state properties and in the spectral function of the system. We characterize the metal-insulator transition between altermagnetic phases at half-filling and the stability of altermagnetism as a function of doping. The calculation of the single-particle spectral function displays the spin-split nature of the electronic excitations, also within the Mott insulating regime. We discuss possible realizations of the model in the context of organic $\alpha$- or $\kappa$-(BEDT-TTF)$_2$X charge transfer salts.