Tunnel magnetoresistance in trilayer junctions from first principles: Cr δ-layerδ-layer doped GaN/AlN/GaN (0 0 0 1)

The microscopic mechanism of the tunneling magnetoresistance (TMR) in Cr-doped GaN/AlN/GaN (0 0 0 1) trilayer junctions is studied based on density functional theory calculations. For enhanced performance, we propose δ-Cr-layerδ-Cr-layer doping in GaN, close to the GaN/AlN interfaces. Depending on the doping concentration, Cr dopants produce local metallic (1 ML) or half-metallic (12 and 14 ML) states surrounded by the host semiconductor materials. Very thin AlN barriers are predicted to yield a low TMR effect. These results help explain existing experimental results and are expected to be valuable with regard to the practical fabrication of improved pure semiconductor spintronic devices.