Bidirectional resonant tunneling spin pump

Bidirectional resonant tunneling spin pump

Resonant tunneling-based spin ratchets

We outline a generic ratchet mechanism for creating directed spin-polarized currents in ac-driven double well or double dot structures by employing resonant spin transfer through the system engineered by local external magnetic fields. We show its applicability to semiconductor nanostructures by considering coherent transport through two coupled lateral quantum dots, where the energy levels of ...

Macroscopic measurement of resonant magnetization tunneling in high-spin molecules.

We report the observation of steps at regular intervals of magnetic field in the hysteresis loop of a macroscopic sample of oriented Mn12O12(CH3COO)16(H2O)4 crystals. The magnetic relaxation rate increases substantially when the field is tuned to a step. We propose that these effects are manifestations of thermally assisted, field-tuned resonant tunneling between quantum spin states, and attrib...

Andreev reflection resonant tunneling through a precessing spin

We investigate Andreev reflection (AR) resonant tunneling through a precessing spin which is coupled to a normal metallic lead and a superconducting lead. The formula of the AR conductance at zero temperature is obtained as a function of chemical potential and azimuthal angle of the spin precessing by using the nonequilibrium Green function method. It is found that as the local spin precesses i...

Spin injection in n-type resonant tunneling diodes

We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X-). We have observed a voltage-controlled circular polarization degree from the quantum well emission...