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G. S. Diniz 1 , A. Latgé 2 and S. E. Ulloa 1

Spin manipulation in carbon nanotubes : All electrical spin filtering through spin-orbit interactions. G. S. Diniz 1 , A. Latgé 2 and S. E. Ulloa 1. 1 Department of Physics and Astronomy , Ohio University , Athens -OH

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G. S. Diniz 1 , A. Latgé 2 and S. E. Ulloa 1

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  1. Spin manipulation in carbon nanotubes: All electrical spin filtering through spin-orbit interactions G. S. Diniz1, A. Latgé2 and S. E. Ulloa1 1Departmentof Physics and Astronomy, Ohio University, Athens-OH 2Instituto de Física, UniversidadeFederalFluminense, Niterói-RJ, Brazil Supported by G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  2. Motivation & Outline • Spin-orbit effects can play an important effect on electronic structure of CNT, hence its conductance • Fully electrical manipulation of spin dependent transport • Adsorption of molecules on the CNT’s wall • Uniform radial electric field • Uniform transverse electric field • Chiral field through a line of charge: spin-polarization mechanism Gang Lu et al,Nano Letters, 5, 897 (2005). A. N. Enyashinet al,Nanotechnology, 18, 245702 (2007). G. S. Diniz, A. Latgéand S. E. Ulloa E. J. Meleet al,PRB, 77, 085429 (2008). F. Kummethet al,Nature, 452, 448 (2008). Dallas, APS March Meeting 2011

  3. Theoretical Model: the system Tight-binding Hamiltonian including spin-orbit effects Htotal= HL + HLC + HC + HCR + HR Hamiltonian for the Central Conductor Intrinsic Term RashbaTerm δ1 δ2 δ3 G. S. Diniz, A. Latgéand S. E. Ulloa Kane & Mele,PRL 95, 146802 (2005). Shenget al,PRL 95, 136602 (1998). Dallas, APS March Meeting 2011

  4. Theoretical Model: conductance G. S. Diniz, A. Latgéand S. E. Ulloa M. B. NardelliPRB 60, 7828 (1999). Lopez Sanchoet al, J. Phys. F: Met. Phys 14, 1205 (1984). Dallas, APS March Meeting 2011 Green’s Function for the Central Conductor with Self-Energies Green’s function for the left/right leads obtained through an iterative procedure The Spin-Polarized Conductance @ the Central Conductor Using the Landauer’s Formula Where the Couplings are Related to the Self-Energies

  5. Numerical Results: SOI manipulation Broken charge conjugation symmetry Broken charge conjugation symmetry Uniform Radial Field (9,0) (10,0) G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  6. Numerical Results: length dependence Uniform Radial Field (9,0) (10,0) G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  7. Numerical Results: SOI manipulation (n,0) CNT atom along CNT’s circumference Tranverse Field (9,0) (10,0) G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  8. Numerical Results: length dependence Transverse Field (9,0) (10,0) G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  9. Numerical Results: chiral model A helical line of charge B A helical line along 30 degrees: “AAA-type” helical line along 60 degrees: “ABA-type” Chiral Field Image credit: V. I. Puller et al.EPL 77, 27006 (2007). All results are for (9,0) G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  10. Numerical Results: chiral field G. S. Diniz, A. Latgéand S. E. Ulloa 4 units cell long 5 units cell long Dallas, APS March Meeting 2011

  11. Numerical Results: chiral field Along “AAA” pitch≈ 3.907 nm G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  12. Numerical Results: chiral field Along “ABA” pitch≈ 1.345 nm G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

  13. Conclusions • Uniform radial and transverse fields in presence of SO interactions do not break TRS • Tube length is quite important when studying SOI • Manipulation of SOR and SOIis reflected in the transmission, providing a way to measure the SOI and SORparameters as well as controlling the current through the CNTs • Chiral field breaks TRS allowing spin-filtering mechanism through SOI • Possible utilization of CNTs in molecular sensing devices exploring SO effects Thanks for you attention! G. S. Diniz, A. Latgéand S. E. Ulloa Dallas, APS March Meeting 2011

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