In some physical systems, the inherent coupling between spatial and magnetic degrees of freedom – the spin-orbit interaction – can lead to a variety of interesting physical phenomena such as the Zitterbewegung (‘trembling motion’) of wave packets and the spin Hall effect [1]. Interestingly, in condensed matter systems the spin-orbit strength can be altered electrically. This offers the unique possibility for spin control via electrical means, i.e., by changing the electron trajectory or wave function via an electric field one can manipulate its spin due to the spin-orbit coupling. This idea underlies many proposals for ‘spin transistors’ [2], possibly more efficient and faster than the
conventional ones. More recently, clever arrangements of crossed lasers and magnetic fields have been used to trap and cool atoms in optical lattices and also to create light-induced gauge potentials [3], which mimic the spin-orbit interactions in real solids (e.g., those of Rashba and
Dresselhaus). In this talk, I will review the basics of the spin-orbit interaction, briefly discuss related novel effects and exploit the possibility of ‘cross-dressing’ atoms [4] to simulate a recently proposed spin-orbit term present in two-dimensional electron systems with two subbands.
This new spin-orbit interaction can give rise to a very peculiar Zitterbewegung with cycloidal orbits without magnetic fields [5].
Cross-dressed atoms as effective spins can provide a proper setting in which to observe this effect, as the relevant parameter range of spin-orbit strengths may be more easily attainable in this context. Analogies between trapped bosonic condensates and spin-polarized fermionic quantum
Liquids [6] will also possibly be addressed. I thank my collaborators Poliana H. Penteado, Fabiano Prado, G. Neto and Miled H. Y. Moussa in this work, and acknowledge support from FAPESP and CNPq.
[1] For a recent overview on spintronics see: Awschalom and Flatté Nat. Phys. 3, 153 2007.
[2] Datta and Das, APL 56, 655 (1990); Egues, Burkard, & Loss APL 82, 2658 (2003).
[3] Lin, Garcia, and Spielman, Nature 471, 83 (2011).
[4] Penteado, Prado, Neto, Moussa, and Egues (unpublished).
[5] Bernardes et al. PRL 99, 076603 (2007); Calsaverini et al. PRB 78, 155313 (2008).
[6] Freire & Egues, PRL 99, 026801 (2007); Ferreira, Freire & Egues, PRL 104, 066803 (2010).
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