We investigate possible spin-dependent resonant tunneling through double-barrier electromagnetic structure. We point out that previous related studies contain serious errors in the calculation and the correct ones show much reduced spin polarization in the tunneling. In this study, we show that the significant amount of spin polarization with nice resonant structures can be achieved by applying a proper electric field subject to the given magnetic barriers. The electric potential U, which is crucial in our model, is chosen to exactly cancel the A2 term originated from the applied magnetic field. In this way, we can remove unwanted obstacles and expedite the tunneling of electrons.
CdZnTe has been characterized by means of polarization-field hysteresis and current–voltage measurements. The CdZnTe is shown to be ferroelectric with polarization endurance up to 107 poling cycles. The polarization is significantly influenced by free carriers and can be switched by light illumination. The capacitance of CdZnTe consists of ferroelectric and depletion components. On the other hand, electrical conduction in the CdZnTe is modulated by the polarization, leading to hysteresis in the current–voltage characteristics. Writing and reading measurement has shown a reading-current difference of 0.015 mA at a nondestructive voltage for the binary digits.
The magnetic properties of a p-type ZnMnO diluted magnetic semiconductor quantum well are investigated by a numerical self-consistent field calculation taking into account the spin-exchange interaction between free carriers and magnetic impurities and the carrier exchange-correlation interaction based on the mean field theory of carrier-induced ferromagnetism. The dependence of the carrier spin polarization on magnetic impurity density and the spin-exchange interaction energy is presented in comparison with well-known III-V-based diluted magnetic semiconductors. The results show that room temperature operation of ZnMnO-based spin devices is probably easier than that of any other materials investigated with the same numerical method.
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