Enhanced spin-current generation in Dirac altermagnets through Klein tunneling

TL;DR

This paper demonstrates that Klein tunneling in Dirac altermagnets can significantly enhance and control spin-current polarization, especially in g-wave cases, offering a new mechanism for spintronic device functionality.

Contribution

It introduces Klein tunneling as a spin-dependent mechanism for controlling spin currents in Dirac altermagnets, highlighting the role of wave symmetry and potential barriers.

Findings

Klein tunneling is strongly spin-dependent in Dirac altermagnets.

Potential barriers can significantly boost spin-current polarization.

g-wave Dirac altermagnets show the most promising spin control via gating.

Abstract

Altermagnets have recently emerged as a new platform for spintronics applications, offering spin-split electronic bands despite vanishing net magnetization. Here, we investigate spin-current generation in Dirac altermagnets and identify Klein tunneling as an efficient mechanism for enhancing spin transport. Using a low-energy Dirac model combined with scattering theory, we demonstrate that Klein tunneling in altermagnets is strongly spin-dependent and can be used to effectively control the electronic spin-current polarization by, for instance, adjusting the height, width and orientation of the potential barrier. Finally, we explore how the l-wave symmetry of the Dirac altermagnet shapes the spin-current polarization and transmission, focusing especially on the d- and g-wave cases. Particularly promising results are obtained for the g-wave Dirac altermagnet, as it is found that the presence of a potential barrier can significantly boost the spin-current polarization, even when the intrinsic polarization due to the spin-split band structure is vanishingly small. For a barrier implemented via electrostatic gating, such a mechanism would in turn allow the spin-current polarization to be switched on and off via a gate voltage.