Intrinsic oscillations of spin current polarization in a paramagnetic resonant tunneling diode

TL;DR

This paper investigates THz oscillations in spin-polarized currents within a paramagnetic resonant tunneling diode, revealing their origin from coupled resonance states and potential applications in spin current generation.

Contribution

It demonstrates the occurrence of THz oscillations in spin currents under steady bias and magnetic field, and introduces a simplified one-electron model confirming the results.

Findings

Spin-up and spin-down currents exhibit THz oscillations under bias.

Oscillations originate from coupling between resonance states.

Potential for spin current THz generator applications.

Abstract

A spin- and time-dependent electron transport has been studied in a paramagnetic resonant tunneling diode using the self-consistent Wigner-Poisson method. Based on the calculated current-voltage characteristics in an external magnetic field we have demonstrated that under a constant bias both the spin-up and spin-down current components exhibit the THz oscillations in two different bias voltage regimes. We have shown that the oscillations of the spin-up (down) polarized current result from the coupling between the two resonance states: one localized in the triangular quantum well created in the emitter region and the second localized in the main quantum well. We have also elaborated the one-electron model of the current oscillations, which confirms the results obtained with the Wigner-Poisson method. The spin current oscillations can lower the effectiveness of spin filters based on the paramagnetic resonant tunneling structures and can be used to design the generators of the spin polarized current THz oscillations that can operate under the steady bias and constant magnetic field.