Double stranded antiferromagnetic helix as an efficient spin filter

Abstract

We report a large degree of spin filtration in a double stranded (ds) antiferromagnetic helix (AFH) system. Generally spin channel separation is not possible when a magnetic system possesses a vanishing net magnetization. But we show that a highly polarized spin current can be obtained through the ds AFH when it is subjected to a transverse electric field. Describing the physical system within a tight-binding framework, spin-dependent transport phenomena are studied using the well known Green’s function formalism. The effects of chirality (left-handed and right-handed), electric field, electronic hopping (short-range and long-range) in each strand, system temperature, and size of the helix on spin filtration are critically investigated. Two different configurations of magnetic moments in the helix are taken into account, for a more general description. Suitably adjusting the physical parameters, almost cent percent spin polarization can be substantiated and that feature persists even for a broad parameter range. Our analysis may open up a new direction for achieving spin-selective electron transmission and designing of controlled spintronic devices using similar kinds of fascinating helical magnetic systems.

Keywords

• Spin filtration
• Double stranded antiferromagnetic helix
• Transverse electric field
• Tight-binding framework
• Beyond nearest-neighbor hopping
• Green’s function formalism