Bias-controlled ultrafast demagnetization in magnetic tunnel junctions

Bias-controlled ultrafast demagnetization in magnetic tunnel junctions

Anomalous bias dependence of spin torque in magnetic tunnel junctions.

We predict an anomalous bias dependence of the spin transfer torque parallel to the interface, Tparallel, in magnetic tunnel junctions, which can be selectively tuned by the exchange splitting. It may exhibit a sign reversal without a corresponding sign reversal of the bias or even a quadratic bias dependence. We demonstrate that the underlying mechanism is the interplay of spin currents for th...

Magnetic Tunnel Junctions

Application of Bardeen’s tunneling theory to magnetic tunnel junctions having a general degree of atomic disorder reveals the close relationship between magneto-conduction and voltage-driven pseudo-torque, as well as the thickness dependence of tunnel-polarization factors. Among the results: 1) The torque generally varies as sin θ at constant applied voltage. 2) Whenever polarization factors ar...

Voltage-controlled interlayer coupling in perpendicularly magnetized magnetic tunnel junctions

Magnetic interlayer coupling is one of the central phenomena in spintronics. It has been predicted that the sign of interlayer coupling can be manipulated by electric fields, instead of electric currents, thereby offering a promising low energy magnetization switching mechanism. Here we present the experimental demonstration of voltage-controlled interlayer coupling in a new perpendicular magne...

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 ma...