Spin-polarized transport properties of GdN nanocontacts

Abstract

Gadolinium nitride (GdN) nanocontacts were recently experimentally shown to be efficient spin filters. Our study is aimed at identifying and analyzing the physical processes responsible for the high spin polarization of the tunneling current in GdN nanostructures. By the example of planar contacts and atomic chains attached to Cu electrodes we assert, using first principle techniques, that a 100% spin-filtering effect can be indeed achieved in GdN nanocontacts. Our analysis shows that the spin filtering is due to the predominant role of nitrogen majority p states in the electron transport, while minority conductance decays exponentially with contact size due to the presence of a minority band gap at the Fermi level. Additionally, GdN zigzag infinite chains are found to be as efficient spin filters as their planar contact counterparts, also exhibiting a 100% spin-filtering effect, which is robust against chain geometry changes.

Gate control of spin-polarized conductance in alloyed transitional metal nanocontacts

“…Finally, in the light of the spintronics application claims the question is bound to arise as to how the spin-polarization of conductance (controlled by the gate potential) shall be detected or further utilized. Without pretending to suggest a market ready solution we shall remark on but a few of the numerous ways of using spinpolarized current, namely by introducing another polarized barrier in the leads (by means of a spin-filtering layer 25 or by sampling the electrons from the edge-state of a spin-hall lead 53 ) thus creating (in optical terms) a crossed polarizer or polarizer-analyzer setup.…”

“…Without pretending to suggest a market ready solution we shall remark on but a few of the numerous ways of using spinpolarized current, namely by introducing another polarized barrier in the leads (by means of a spin-filtering layer 25 or by sampling the electrons from the edge-state of a spin-hall lead 53 ) thus creating (in optical terms) a crossed polarizer or polarizer-analyzer setup.…”

“…[18][19][20] The tunability, or the susceptibility of spin-dependent transport properties 21,22 to external perturbations can be achieved in several ways. Orientation and ordering of spins in magnetic systems can be "programmed" into atomic-scale junctions at construction stage (e.g., by tuning the chemical composition and geometry of the device 4,7,[17][18][19][23][24][25] ), but it is even more important and challenging to be able to dynamically and reversibly tune those properties after the junction has been completed or integrated into a circuit. The "traditional" way of controlling transmission properties of both conventional and single-electron transistors is the field effect, i.e.…”

Device Applications of Rare-Earth Nitrides

“…for thick >10 nm layers [14,87]. For a 100% polarisation, Equation 4.1 leads to an infinite TMR, making magnetic semiconductors interesting candidates for large TMR values 2 .…”