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Rashbons: properties and their significance

Vyasanakere, Jayantha P and Shenoy, Vijay B (2012) Rashbons: properties and their significance. In: NEW JOURNAL OF PHYSICS, 14 .


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Official URL: http://dx.doi.org/10.1088/1367-2630/14/4/043041


In the presence of a synthetic non-Abelian gauge field that produces a Rashba-like spin-orbit interaction, a collection of weakly interacting fermions undergoes a crossover from a Bardeen-Cooper-Schrieffer (BCS) ground state to a Bose-Einstein condensate (BEC) ground state when the strength of the gauge field is increased (Vyasanakere et al 2011 Phys. Rev. B 84 014512). The BEC that is obtained at large gauge coupling strengths is a condensate of tightly bound bosonic fermion pairs. The properties of these bosons are solely determined by the Rashba gauge field-hence called rashbons. In this paper, we conduct a systematic study of the properties of rashbons and their dispersion. This study reveals a new qualitative aspect of the problem of interacting fermions in non-Abelian gauge fields, i.e. that the rashbon state ceases to exist when the center-of-mass momentum of the fermions exceeds a critical value that is of the order of the gauge coupling strength. The study allows us to estimate the transition temperature of the rashbon BEC and suggests a route to enhance the exponentially small transition temperature of the system with a fixed weak attraction to the order of the Fermi temperature by tuning the strength of the non-Abelian gauge field. The nature of the rashbon dispersion, and in particular the absence of the rashbon states at large momenta, suggests a regime in parameter space where the normal state of the system will be a dynamical mixture of uncondensed rashbons and unpaired helical fermions. Such a state should show many novel features including pseudogap physics.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Thomson Reuters
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 10 Jul 2012 07:17
Last Modified: 10 Jul 2012 07:20
URI: http://eprints.iisc.ac.in/id/eprint/44601

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