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Title: Continuum model for chiral induced spin selectivity in helical molecules

A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented p{sub z} type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the spin-orbit coupling (SOC) opens up an effective π{sub z} − π{sub z} coupling via interbase p{sub x,y} − p{sub z} 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 (i) which spin orientation is selected depending on chirality and bias, (ii) changes in spin preference as a function of input Fermi level and (iii) back-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.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [1] ;  [2]
  1. Centro de Física, Instituto Venezolano de Investigaciones Científicas, 21827, Caracas 1020 A (Venezuela, Bolivarian Republic of)
  2. (France)
  3. (United States)
  4. IMDEA Nanoscience, Cantoblanco, 28049 Madrid (Spain)
  5. Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States)
Publication Date:
OSTI Identifier:
22415802
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BACKSCATTERING; CHIRALITY; ELECTRONS; EXACT SOLUTIONS; FERMI LEVEL; HELICITY; L-S COUPLING; MOLECULES; SPIN; SPIN ORIENTATION; T INVARIANCE; TEMPERATURE RANGE 0273-0400 K