Spintronic I: Spin-orbit interaction in symmetric 2DEGs

• Grant number: 06/04227-6
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2006
• End date: October 31, 2009
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Esmerindo de Sousa Bernardes
• Grantee: Esmerindo de Sousa Bernardes
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

We investigate the spin-orbit (s-o) interaction in two-dimensional electron gases (2DEGs) formed in quantum wells with two sub-bands. Startingfrom the 8x8 Kane model, we find a new inter band-induced s-o coupling which resembles the functional form of the ordinary Rashba s-o in 2DEGs -- but occurs even for symmetric structures. This follows from the distinct parity of the confined states (even/odd) which obliterates the need for asymmetric potentials. For symmetric square and parabolic wells our s-ocoupling is comparable to the usual Rashba constant and gives rise to zitterbewegung of electronic wave packets superimposed on cyclodal trajectories in the absence of magnetic fields. We predict a sizable effective mass renormalization due to the band-warping induced by our new s-o term. Also, we found the same Dirac equation for an electron moving in our symmetric 2DEG. We believe this can improve the possibility of using semiconductor nanostructures to explore, in a direct way, the surprising outcomes of the Dirac equation known since 1928 but some of that lacking any direct observation. (AU)