Spin-polarized localization in a magnetized chain

Leonardo Benini,Arunava Chakrabarti,Rudolf A Römer,Amrita Mukherjee

doi:10.1038/s41598-019-42316-5

Leonardo Benini, Arunava Chakrabarti + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-42316-5

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Journal: Scientific Reports	Publication Date: Apr 11, 2019
Citations: 14	License type: open-access

Affiliation: University of Warwick, University of Kalyani

Abstract

We investigate a simple tight-binding Hamiltonian to understand the stability of spin-polarized transport of states with an arbitrary spin content in the presence of disorder. The general spin state is made to pass through a linear chain of magnetic atoms, and the localization lengths are computed. Depending on the value of spin, the chain of magnetic atoms unravels a hidden transverse dimensionality that can be exploited to engineer energy regimes where only a selected spin state is allowed to retain large localization lengths. We carry out a numerical anmalysis to understand the roles played by the spin projections in different energy regimes of the spectrum. For this purpose, we introduce a new measure, dubbed spin-resolved localization length. We study uncorrelated disorder in the potential profile offered by the magnetic substrate or in the orientations of the magnetic moments concerning a given direction in space. Our results show that the spin filtering effect is robust against weak disorder and hence the proposed system should be a good candidate model for experimental realizations of spin-selective transport devices.

Highlights

We investigate a simple tight-binding Hamiltonian to understand the stability of spin-polarized transport of states with an arbitrary spin content in the presence of disorder
We have investigated the robustness of spin-polarized transport through a linear array of magnetic atoms depicted in a random landscape
Band gaps are engineered by controlling the strength of the field, and spin-resolved localization lengths are estimated in every case

Summary

Introduction

We investigate a simple tight-binding Hamiltonian to understand the stability of spin-polarized transport of states with an arbitrary spin content in the presence of disorder. Spintronics exploits the ability of conduction electrons to carry a spin-polarized current[4], and relies heavily on long decoherence time and length scales, and leads to the elegance of multifunctionality, an increased data processing speed and less power consumption[5] It is pivotal in quantum information technology and has opened up the possibility of developing quantum computers. A simple quantum interferometer, designed in the shape of a single mode ring and threaded by a magnetic flux[19,20], has proven to be a well-suited object to understand the interplay of a closed loop geometry and a trapped magnetic flux in terms of the path-breaking Aharonov-Bohm (AB) effect[21] Such a simple system with a two-terminal lead geometry was later exploited[22] to study the anisotropic spin transport in the presence of the Rashba and Dresselhaus spin-orbit interactions[23,24]. The random orientations of the field vector represent the disorder in the magnetic field

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