Orbital-Splitter Current in Altermagnets

TL;DR

This paper introduces the orbital-splitter current (OSC) in altermagnets, deriving its properties, and demonstrates its significant magnitude and effects, such as torque generation and reduced magnetization switching time.

Contribution

It defines and analyzes the orbital-splitter current in altermagnets, revealing its intrinsic nature, anisotropic response, and impact on magnetization dynamics.

Findings

OSC in FeSb₂ is purely intrinsic due to symmetry constraints.

OSC exceeds spin-splitter current by nearly four times in certain orientations.

OSC generates damping-like torque, reducing magnetization switching time.

Abstract

In collinear altermagnets, the real-space rotational symmetry of opposite spin sublattices generates a large nonrelativistic spin-splitter current. Orbital transport in this setting has remained largely unexplored. Here, we introduce the orbital-splitter current (OSC), an orbital analogue of the spin-splitter current, and derive its Drude and orbital Berry curvature contributions using a density-matrix framework. We show that the $d$-wave altermagnet $\mathrm{FeSb}_2$ realizes a purely intrinsic OSC because mirror symmetries suppress the Drude channel by forcing the orbital magnetic moment to vanish. The OSC response is strongly anisotropic and, for selected field orientations, exceeds the spin-splitter current by nearly a factor of four. We further show that the OSC generates a damping-like torque in an altermagnet-ferromagnet heterostructure and, when combined with the spin-splitter current, significantly reduces the magnetization switching time.