Controlling the spin conductance in a graphene zigzag hexagonal quantum ring connected to three leads in the presence of spin-orbit interaction and magnetic field

Document Type : Full length research Paper

Authors

1 Member of school of physics Iran University Science and Technology

2 school of physics, Iran university of scions and technology, Tehran, Iran

Abstract

In this work, we theoretically investigate the spin dependent conductance and polarization in a Hexagonal graphene ring (HGR) with zigzag edges connected to three semi-infinite leads in the presence of a perpendicular magnetic flux and Rashba spin-orbit interaction (RSOI). Results are obtained using the tight-binding model within the non-equilibrium Green’s function formalism and suggest that in the absence of magnetic flux, for appropriate values of Rashba strength and energy of the incoming electrons; high spin-polarized conductances with opposite direction can be obtained for right up and right down leads, respectively. In this case, the system can act as a spin spliting device. In addition, it is found that by applying a magnetic flux to the central region of the HGR, it is possible to determine the magnitude and direction of polarization in output leads due to the time reversal breaking so, the system can be consider as a good candidate for the spintronic applications.

Keywords


 
[1] I. Zutic, J. Fabian, S. Das Sarma, Spintronics: Fundamentals and applications, Reviews of modern physics, 76(2004),323.
 
[2] H. Dery, P. Dalal, L. Cywinski, L.J. Sham, Spin-based logic in semiconductors for reconfigurable large-scale circuits, Nature 447 (2007) 573.
 
[3] K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, Y. Zhang, S.V. Dubonos, IV. Grigorieva, A.A. Firsov, Electric field effect in atomically thin carbon films, Science 306 (2004) 666-669.
 
[4] S.D. Sarma, S. Adam, E.H. Hwang, E. Rossi, Reviews of Modern Physics, Electronic transport in two-dimensional graphene, Reviews of Modern Physics 83 (2011) 407.
 
[5] K.S.A. Novoselov, A.K. Geim, S. Morozov, D. Jiang, M. Katsnelson, I. Grigorieva, A. Firsov, Two-dimensional gas of massless Dirac fermions in graphene, nature 438 (2005) 197-200.
 
[6] J.W. Jiang, J.S.Wang,B. Li,Thermal conductance of graphene and dimerite, Physical Review B 79 (2009) 205418.
 
[7] W. Jang, Z. Chen, W. Bao, C.N. Lau, C. Dames, Thickness -dependent thermal conductivity of encased graphene and ultrathin graphite, Nano letters 10 (2010) 3909-3913.
 
[8] N. Tombros, C. Jozsa, M., Popinciuc, H.T. Jonkman, B.J. van Wees, Electronic spin transport and spin precession in single graphene layers at room temperature, Nature 448 (2007) 571.
 
[9] T.Y. Yang, J. Balakrishnan, F. Volmer, A. Avsar, M. Jaiswal, J. Samm, S.R. Ali, A. Pachoud, M. Zeng, M. Popinciuc, G. Güntherodt, B. Beschoten, B. Özyilmaz, Observation of long spin-relaxation times in bilayer graphene at room temperature, Physical review letters 107 (2011) 047206.
 
[10] D.D. Awschalom, M.E. Flatté, Challenges for semiconductor spintronics, Nature Physics 3, (2007) 153-159.
 
[11] N. Tombros, C. Jozsa, M. Popinciuc, H.T. Jonkman, Electronic spin transport and spin precession in single graphene layers at room temperature, Nature, 448 (2007) 571-574.
 
[12] E.I. Rashba, Properties of semiconductors with an extremum loop. 1. Cyclotron and combinational resonance in a magnetic field perpendicular to the plane of the loop, Soviet Physics - Solid State 2 (1960) 1224-1238.
[13] Z.Y. Li, Z.Q. Yang, S. Qiao, J. Hu, R.Q. Wu, Spin–orbit splitting in graphene on metallic substrates, Journal of Physics: Condensed Matter 23 (2011) 225502.
 
[14] H. Hiura, Tailoring graphite layers by scanning tunneling microscopy, Applied surface science 222 (2004) 374-381.
 
[15] S. Schnez, F. Molitor, C. Stampfer, J. Güttinger, I. Shorubalko, T. Ihn, K. Ensslin, Observation of excited states in a graphene quantum dot, Applied Physics Letters 94 (2009) 012107.
 
[16]J. Schelter, P. Recher, B. Trauzettel,The Aharonov–Bohm effect in graphene rings, Solid State Communications 152 (2012) 1411-1419.
 
[17] D. Smirnov, H. Schmidt, R.J. Haug, Aharonov-Bohm effect in an electron-hole graphene ring system, Applied Physics Letters 100 (2012) 203114.
 
[18] M. Huefner, F. Molitor, A. Jacobsen, A. Pioda, C. Stampfer, K. Ensslin, T. Ihn, Investigation of the Aharonov–Bohm effect in a gated graphene ring, physica status solidi (b) 246 (2009) 2756-2759.
 
[19] P. Recher, B. Trauzettel, A. Rycerz, Ya. M. Blanter, C.W.J. Beenakker, A.F. Morpurgo, Aharonov-Bohm effect and broken valley degeneracy in graphene rings, Physical Review B 76 (2007) 235404.
 
[20] M. Saiz-Bretín, J. Munárriz, A.V. Malyshev, F. Domínguez-Adame, Control of spin-polarised currents in graphene nanorings, Physics letters A 379 (2015) 2102-2105.
 
[21] D. Faria, R. Carrillo-Bastos, N. Sandler, A. Latgé, Fano resonances in hexagonal zigzag graphene rings under external magnetic flux, Journal of Physics: Condensed Matter 27 (2015) 175301.
 
[22] M.I. Katsnelson, K.S. Novoselov, A.K. Geim, Chiral tunnelling and the Klein paradox in graphene, Nature physics 2 (2006) 620-625.
 
[23] M.P.L. Sancho, J.M.L. Sancho, J. Rubio, Quick iterative scheme for the calculation of transfer matrices: application to Mo (100), Journal of Physics F: Metal Physics 14(1984) 1205.
 
[24] S. Datta, Electronic Transport in Mesoscopic Systems, Cambridge University Press, Cambridge, (1995).
 
[25] Y. Imry, R. Landauer, Conductance Viewed as Transmission, Reviews of Modern Physics 71 (1999) 515-525.