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Spin-Dependent Scattering From Gated Obstacles in Graphene Systems

Spin-Dependent Scattering From Gated Obstacles in Graphene Systems . M.M. Asmar & S.E. Ulloa Ohio University . Outline . Motivation. The studied system and the mathematical approach. Results and analysis. Conclusions. Motivation .

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Spin-Dependent Scattering From Gated Obstacles in Graphene Systems

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  1. Spin-Dependent Scattering From Gated Obstacles in Graphene Systems M.M. Asmar & S.E. Ulloa Ohio University

  2. Outline • Motivation. • The studied system and the mathematical approach. • Results and analysis. • Conclusions.

  3. Motivation • Because of the high importance of spintronicson which the spin orbit interactions play a basic role, we study and compare the relaxation times in the presence of a gated potential to the relaxation times in the presence of SOI in graphene systems. • The importance of the relaxation times is based on their proportionality to the conductance of the system.

  4. The studied system and the mathematical approach The Hamiltonian of the system:

  5. C. L. Kane and E. J. Mele, PRL 95, 226801 (2005). Wave functions (at K point) are : Total angular momentum m and , From the analytical form of the wave function we can extract some information such as • Phase shifts • Differential cross sections • Total cross sections • Transport cross section which is inversely proportional to the relaxation time • Conductance, which is proportional to the relaxation time

  6. In the presence of a gated obstacle and no SOI • J. Milton Pereira, Jr., V. Mlinar, and F. M. Peeter, P RB 74, 045424 (2006) Results and Analysis Ramsauer-Townsend Effect at V/2

  7. C. L. Kane and E. J. Mele, PRL 95, 226801 (2005). • Daniel Huertas-Hernando, F. Guinea,and Arne Brataas1, PRB 74, 155426 (2006). In the presence gated obstacles and Intrinsic SOI

  8. Gierz, et al., arXiv:1004.1573. • J. Sánchez-Barriga, et al. , Diamond & Related Materials 19 (2010) 734–74 In the presence of the gated obstacle and Rashba SOI Comparable relaxation times

  9. A.H. Castro Neto and F. Guinea, PRL 103, 026804 (2009). • N. Tombros et al., Nature (London) 448, 571 (2007). Longer spin flip relaxation times

  10. In the presence of the gated obstacle RSOI and ISOI

  11. Conclusions • Quasi bound states reflect themselves as resonances in the cross section. • Intrinsic SO decreases the scattering time and shifts the resonances in the cross section. • Spin flip relaxation times are much longer that the momentum relaxation times at low energies. • Momentum and spin-flip scattering times are comparable at relatively high energies. • Spin flip times and momentum relaxation times are equal at both the K and K’ point.

  12. Thank You

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