Zitterbewegung of electrons in quantum wells and dots in presence of an in-plane magnetic field

TL;DR

This paper investigates how an in-plane magnetic field influences the zitterbewegung (electron trembling motion) in semiconductor quantum wells and dots with spin-orbit interactions, revealing conditions that sustain or enhance this motion.

Contribution

It provides a general expression for electron position evolution in quantum wells and demonstrates how magnetic fields affect zitterbewegung, including its persistence under various conditions.

Findings

Magnetic field sustains ZB in quantum wells even at low wavevector values.

High g-factor materials exhibit long-lasting ZB.

Quantum dots show multi-frequency ZB due to energy eigenvalue differences.

Abstract

We study the effect of an in-plane magnetic field on the zitterbewegung (ZB) of electrons in a semiconductor quantum well (QW) and in a quantum dot (QD) with the Rashba and Dresselhaus spin-orbit interactions. We obtain a general expression of the time-evolution of the position vector and current of the electron in a semiconductor quantum well. The amplitude of the oscillatory motion is directly related to the Berry connection in momentum space. We find that in presence of the magnetic field the ZB in a quantum well does not vanish when the strengths of the Rashba and Dresselhaus spin-orbit interactions are equal. The in-plane magnetic field helps to sustain the ZB in quantum wells even at low value of $k_0 d$ (where $d$ is the width of the Gaussian wavepacket and $k_0$ is the initial wave vector). The trembling motion of an electron in a semiconductor quantum well with high Lande g-factor (e.g. InSb) sustains over a long time, even at low value of $k_0 d$. Further, we study the ZB of an electron in quantum dots within the two sub-band model numerically. The trembling motion persists in time even when the magnetic field is absent as well as when the strengths of the SOI are equal. The ZB in quantum dots is due to the superposition of oscillatory motions corresponding to all possible differences of the energy eigenvalues of the system. This is an another example of multi-frequency ZB phenomenon.