Zero-Bias Anomaly in Magnetic Tunnel Junctions

Theory of the zero-bias anomaly in magnetic tunnel junctions: Inelastic tunneling via impurities

Using the closed-time path-integral approach, we nonperturbatively study inelastic tunneling of electrons via magnetic impurities in the barrier accompanied by phonon emission in a magnetic tunnel junction. The spectrum density of phonon emission is found to show a power-law infrared singularity ,v−s1−gd with g the dimensionless electron-phonon coupling. As a consequence, the tunneling conducta...

Zero-bias anomaly in CrO2 junctions

– CrO2 thin films, with crystallites of several microns size, provide the opportunity for the investigation of the intergrain tunneling between a few crystals separated by a 1–2 nm thick Cr2O3 film. A pronounced zero-bias anomaly of the conductance is found at low temperatures. Combined photoemission and inverse photoemission temperature-dependent studies confirm the occurrence of Coulomb block...

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...