Dimensionality effects in the LDOS of ferromagnetic hosts probed via STM: spin-polarized quantum beats and spin filtering

TL;DR

This paper theoretically explores how the local density of states (LDOS) in ferromagnetic hosts varies with system dimensionality, revealing spin-polarized quantum beats and demonstrating the quantum wire's potential as an efficient spatial spin filter.

Contribution

It provides analytical expressions for LDOS in different host geometries and uncovers the impact of dimensionality on spin-dependent quantum interference effects.

Findings

LDOS exhibits Friedel-like oscillations and Fano interference.

Spin-polarized quantum beats depend on host dimension.

Quantum wire acts as an efficient spatial spin filter.

Abstract

We theoretically investigate the local density of states (LDOS) probed by a STM tip of ferromagnetic metals hosting a single adatom and a subsurface impurity. We model the system via the two-impurity Anderson Hamiltonian. By using the equation of motion with the relevant Green functions, we derive analytical expressions for the LDOS of two host types: a surface and a quantum wire. The LDOS reveals Friedel-like oscillations and Fano interference as a function of the STM tip position. These oscillations strongly depend on the host dimension. Interestingly, we find that the spin-dependent Fermi wave numbers of the hosts give rise to spin-polarized quantum beats in the LDOS. While the LDOS for the metallic surface shows a damped beating pattern, it exhibits an opposite behavior in the quantum wire. Due to this absence of damping, the wire operates as a spatially resolved spin filter with a high efficiency.