Magnetic Tunnel Junctions

Figure 1 Schematic illustration showing the mechanism of TMR. Top: for parallel aligned magnetization as sketched at left, electrons around the Fermi level with spin up (m) and spin down (k) are allowed to tunnel from majority to majority bands, and from minority to minority bands. Bottom: when the magnetization is antiparallel, tunneling takes place from majority to minority and minority to majority bands, leading to a reduction of total tunneling current. In terms of electrical resistance, this corresponds to a higher resistance when the magnetization of the two layers is oppositely aligned. Introduction