Groupe de Physique Statistique

Equipe 106, Institut Jean Lamour

                     
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Séminaire de groupe

Spin transport along chiral molecules
Ernesto Medina
IVIC
jeudi 03 décembre 2015 , 11h00
Salle de séminaire du groupe de Physique Statistique

A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented pz type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the SOC opens up an effective piz−piz coupling via interbase px,y−pz hopping, introducing spin coupled transport. The resulting continuum model spectrum shows two Kramers doublet transport channels with a gap proportional to the SOC. Each doubly degenerate channel satisfies time reversal symmetry, nevertheless, a bias chooses a transport direction and thus selects for spin orientation. The model predicts which spin orientation is selected depending on chirality and bias, changes in spin preference as a function of input Fermi level and scattering suppression protected by the SO gap. We compute the spin current with a definite helicity and find it to be proportional to the torsion of the chiral structure and the non-adiabatic Aharonov- Anandan phase. To describe room temperature transport we assume that the total transmission is the result of a product of coherent steps limited by the coherence length.

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