Orbital-driven emergent transport in altermagnets

TL;DR

This paper extends the understanding of altermagnets by incorporating orbital degrees of freedom, revealing emergent electric fields and multipole currents influenced by lattice anisotropy and distortions.

Contribution

It introduces a Hamiltonian that includes orbital dynamics, demonstrating controllable emergent electric fields and currents in altermagnets, broadening their potential for spintronics applications.

Findings

Emergent electric fields can be controlled via lattice anisotropy.

Orbital and magnetic multipole currents are demonstrated.

Emergent electric fields can arise from dynamic lattice distortions.

Abstract

Altermagnets have recently emerged as a promising platform for spintronics due to their unique magnetic symmetry. However, most studies have focused on spin degrees of freedom, leaving the dynamic role of orbital degrees of freedom largely unexplored. In this work, we extend the altermagnet Hamiltonian to include the orbital degree of freedom as a dynamical variable and derive the resulting emergent electromagnetic fields (EEMFs). This approach allows us to demonstrate emergent electric fields controllable via lattice anisotropy and the resulting orbital and magnetic multipole currents. Furthermore, we show that non-vanishing emergent electric fields can arise even in simplified spin and orbital textures, particularly in the presence of dynamic lattice distortion. This formalism is generalizable to high-order altermagnets beyond d-wave systems.