• Home
• Browse articles
• About
• Editorial board
• Instructions for authors
• For reviewers
• My details

Research article

Ab-initio calculations of spin tunneling through an indirect barrier

Athanasios N Chantis¹ , Titus Sandu² and Jialei L Xu³

¹Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

²International Centre of Biodynamics, Intrarea Portocalelor Street, Nr.1B, Postal Code 060101, District 6, Bucharest, Romania

³Arizona State University, Tempe, Arizona, 85284, USA

author email corresponding author email

PMC Physics B 2008, 1:13doi:10.1186/1754-0429-1-13

Published:	6  June  2008

Abstract

We use a fully relativistic layer Green's functions approach to investigate spin-dependent tunneling through a symmetric indirect band gap barrier like GaAs/AlAs/GaAs heterostructure along [100] direction. The method is based on Linear Muffin Tin Orbitals and it is within the Density Functional Theory (DFT) in the Local Density Approximation (LDA). We find that the results of our ab-initio calculations are in good agreement with the predictions of our previous empirical tight binding model [Phys. Rev. B, 075313 (2006)]. In addition we show the k_||-dependence of the spin polarization which we did not previously include in the model. The ab-initio calculations indicate a strong k_||-dependence of the transmission and the spin polarization due to band non-parabolicity. A large window of 25–50% spin polarization was found for a barrier of 8 AlAs monolayers at k_|| = 0.03 2π/a. Our calculations show clearly that the appearance of energy windows with significant spin polarization depends mostly on the location of transmission resonances and their corresponding zeros and not on the magnitude of the spin splitting in the barrier.

PACS Codes: 71.70.Ej, 71.15.Mb, 71.55.Eq