Persistent Zitterbewegung of electron wave packet in time-dependent Rashba system
1 Department of Electrical and Computer Engineering, National University of Singapore 4 Engineering Drive 3, Singapore 117576, Singapore
2 Data Storage Institute, Agency for Science, Technology and Research (A*STAR), DSI Building 5 Engineering Drive 1, Singapore 117608, Singapore
Received: 6 July 2014
Accepted: 8 October 2014
The Zitterbewegung (ZB) of an electron wave packet is theoretically studied in a Rashba spin-orbit coupling system, in the presence of the AC gate voltage modulation of α, the Rashba coupling strength. In the absence of AC modulation, the ZB dynamics of a wave packet rapidly decays due to interference from the different wave packet components. Under AC modulation of α, the ZB dynamics may be sustained indefinitely. We quantify two characteristics of this persistent ZB motion as a function of the modulation frequency ω, i.e., the peak amplitude and the regularity RZ of the electron jitter motion. We analytically show that RZ improves with increasing ω. At sufficiently high modulation frequency, the ZB motion becomes totally regular, i.e., with a single characteristic frequency of . On the other hand, at high modulation frequency, the amplitude diminishes asymptotically as . These trends of the ZB dynamics can also be obtained analytically by considering the spin-force picture. Our study provides the reference for achieving sustained large-amplitude and regular ZB oscillations under AC modulation, which is useful for experimental observation of the elusive ZB phenomenon in a Rasbha system.
PACS: 71.70.Ej – Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect / 75.76.+j – Spin transport effects / 03.65.-w – Quantum mechanics
© EPLA, 2014