Spin-dependent transport in a driven noncolinear antiferromagnetic fractal network

TL;DR

This paper investigates spin-dependent transport in a noncolinear antiferromagnetic fractal network, proposing a novel method to significantly enhance spin polarization using a time-periodic driving field, with implications for AFM spintronics.

Contribution

It introduces a new approach to achieve high spin polarization in fractal antiferromagnetic structures via periodic driving, a concept not previously explored.

Findings

Weak intrinsic spin polarization in the unperturbed system.

Significant enhancement of spin polarization with periodic driving.

Dependence of spin polarization on driving parameters and structure size.

Abstract

Noncolinear magnetic texture breaks the spin-sublattice symmetry which gives rise to a spin-splitting effect. Inspired by this, we study the spin-dependent transport properties in a noncolinear antiferromagnetic fractal structure, namely, the Sierpinski Gasket (SPG) triangle. We find that though the spin-up and spin-down currents are different, the degree of spin polarization is too weak. Finally, we come up with a proposal, where the degree of spin polarization can be enhanced significantly in the presence of a time-periodic driving field. Such a prescription of getting spin-filtering effect from an unpolarized source in a fractal network is completely new to the best of our knowledge. Starting from a higher generation of SPG to smaller ones, the precise dependencies of driving field parameters, spin-dependent scattering strength, interface sensitivity on spin polarization are critically investigated. The spatial distribution of spin-resolved bond current density is also explored. Interestingly, our proposed setup exhibits finite spin polarization for different spin-quantization axes. Arbitrarily polarized light is considered and its effect is incorporated through Floquet-Bloch ansatz. All the spin-resolved transport quantities are computed using Green's function formalism following the Landauer-B\"{u}ttiker prescription. The present work brings forth new insights into spintronic properties of noncolinear antiferromagnetic SPG and should entice the AFM spintronic community to explore other fractal structures with the possibility of unconventional features.