Spin separation and filtering assisted by topological corner states in the Kekul\'{e} lattice

TL;DR

This paper demonstrates how topological corner states in a Kekulé lattice can be used to achieve spin separation and filtering, enabling spin-polarized transport controlled by local magnetization and electric potential.

Contribution

It introduces a novel mechanism for spin-dependent transport using topological corner states in a Kekulé lattice, combining spin polarization, filtering, and spatial separation.

Findings

Opposite local magnetization polarizes corner states with opposite spins.

Spin-up and spin-down electrons are perfectly separated in transport.

Electric potential enables selective spin filtering and current generation.

Abstract

Higher-order topological corner states have been realized in two-dimensional Kekul\'{e} lattice, which can be further coupled with spin polarization through the implementation of local magnetization. In this work, we numerically investigate the spin-dependent transport properties assisted by topological corner states in the Kekul\'{e} lattice. By applying local magnetization and electric potential, the topological corner states are spin polarized with opposite spins localized at different corners, thereby demonstrating a spin-corner state locking mechanism. Transport characteristics, including transmission, local density of states, and local current density, are calculated for a two-terminal setup consisting of a diamond-shaped Kekul\'{e} lattice connected to two leads. When opposite local magnetization is applied to the corners, spin-up and spin-down electrons are perfectly separated, forming two spin-polarized conducting channels and leading to spin spatial separation. In the presence of identical local magnetization on both corners and an electric potential at one corner, the spin-polarized corner states can facilitate selective filtering of different spins and generate spin-polarized currents by tuning the energy. Furthermore, spin-resolved transmission diagrams as functions of both the Fermi energy and electric potential are presented, illustrating the global distribution of spin filtering through topological corner states.