Dynamics of Pure Spin Current in High-frequency Quantum Regime

TL;DR

This paper investigates the behavior of pure spin currents at high frequencies in quantum regimes, revealing frequency-dependent noise and oscillations due to quantum effects, which are crucial for spintronic device control.

Contribution

It introduces a mesoscopic transport theory approach to analyze high-frequency spin current dynamics, highlighting quantum-induced noise and oscillatory behavior without net charge flow.

Findings

Frequency-dependent finite noise observed in spin current

Sinusoidal oscillations in autocorrelation due to Pauli exclusion

Spin current dynamics characterized in high-frequency quantum regime

Abstract

Pure spin current is a powerful tool for manipulating spintronic devices, and its dynamical behavior is an important issue. By using mesoscopic transport theory for electron tunneling induced by spin accumulation, we investigate the dynamics of the spin current in the high-frequency quantum regime, where the frequency is much larger than temperature and bias voltage. Besides the thermal noise, frequency-dependent finite noise emerges, signaling the spin current across the tunneling barrier. We also find that the autocorrelation of the spin current exhibits sinusoidal oscillation in time as a consequence of the Pauli exclusion principle even without any net charge current.