Transport theory and spin-transfer physics in d-wave altermagnets

TL;DR

This paper develops a mesoscale transport theory for charge and spin in d-wave altermagnets, revealing unique spin-transfer effects and potential for controlling spin textures like domain walls.

Contribution

It introduces a novel transport framework based on the slave-boson formulation of the t-J model, highlighting spin-splitter effects and complex spin-transfer responses in d-wave altermagnets.

Findings

Identification of a spin-polarized diffusive contribution unique to altermagnets.

Discovery of new charge current and spatial derivative combinations in spin-transfer responses.

Potential for manipulating spin textures such as domain walls using transverse charge currents.

Abstract

We develop a mesoscale transport theory for the charge and spin degrees of freedom of itinerant carriers in a $d$-wave altermagnet. Our effective Lagrangian description is built upon the slave-boson formulation of the microscopic $t-J$ model. We obtain a spin-polarized diffusive contribution to the effective Hamiltonian, with no counterpart in conventional antiferromagnetism and parametrized by the spin splitting, that is responsible for the so-called spin-splitter effect in $d$-wave altermagnets. We also elucidate the spin-transfer response of the itinerant fluid as well as the spin pumping into the altermagnet, which show previously unidentified combinations of the charge current and spatial partial derivatives (namely, {$j_{x}^{e}$,$\partial_{y}$} and {$j_{y}^{e}$,$\partial_{x}$}). The emergent spin-transfer physics in $d$-wave altermagnets opens up new possibilities for the dynamics of spin textures, such as the domain-wall motion driven by transverse charge currents. We also consider the effect of elastic distortions in the aforementioned transport properties.