Temperature Effects on Dynamical Conductivity of Graphene Based Systems

Abstract:

We have investigated dynamical conductivity of graphene based systems; Single Layer Graphene (SLG), Bilayer Graphene (BLG) and Single Layer Gapped Graphene (SLGG), at zero and finite temperatures by taking into the account screening effects within the Random Phase Approximation (RPA). Rσq,ω and Rσq,ω show peaks that correspond to single particle excitations (SPE) and collective excitations (CE) respectively. In SLG, SPE positions are observed at ωħ≈0.5εf,εf∧1.5εf for q0.5kf,kf∧1.5kf respectively for all values of temperature. The peak height increases with increasing electron momentum and temperature. We noticed that for finite momentumq0.5kf∧kf, the peak height is maximum for T=0K and minimum for T=0.5Tf while that for T=Tf is intermediate. We also noticed that Rσq,ω peaks are blue shifted at high temperature for all graphene systems. In case of BLG, Landau undamped peak has been observed at T=0 for finite momentumq=0.3kf which becomes smooth at T=0.5Tf∧Tf. For q=0.8kf, Landau damped plasmon peaks have also been observed for all values of temperature. No major changes are observed in case of SLGG, with respect to SPE and CE peaks positions and heights specifically due to small change in band gap value incorporated here.

• Periodical: Advanced Materials Research (Volume 1141)
• Pages: 6-13
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1141.6
• Online since: August 2016
• Authors: D.K. Patel*, Sagar Ambavale, K.J. Prajapati, A.C. Sharma
• Keywords: Bilayer Graphene, Collective Excitations, Single Layer Gapped Graphene, Single Layer Graphene, Single Particle Excitations

References

[1] Y. Zhang, J. W. Tan, H. L. Stormer and P. Kim, Experimental observation of the quantum Hall effect and Berry's phase in graphene, Nature 438 (2005) 201.

DOI: 10.1038/nature04235

[2] T. Ando and M. Koshino, Optical absorption by interlayer density excitations in bilayer graphene, J. Phys. Soc. Jpn. 78 (2009) 104716.

DOI: 10.1143/jpsj.78.104716

[3] V. P. Gusynin, S. G. Sharapov, Transport of Dirac quasiparticles in graphene: Hall and optical conductivities, Phys. Rev. B 73 (2006) 245411.

DOI: 10.1103/physrevb.73.245411

[4] B. Wunsch, T. Stauber, F. Sols, and F. Guinea, Dynamical polarization of graphene at finite doping, New J. Phys. 8 (2006) 318.

DOI: 10.1088/1367-2630/8/12/318

[5] E. H. Hwang and S. Das Sarma, Dielectric function, screening, and plasmons in two-dimensional graphene, Phys. Rev. B 75 (2007) 205418.

DOI: 10.1103/physrevb.75.205418

[6] M. Koshino and T. Ando, Transport in bilayer graphene: Calculations within a self-consistent Born approximation, Phys. Rev. B 73 (2006) 245403.

DOI: 10.1103/physrevb.73.245403

[7] J. Nilsson, A. H. Castro Neto, F. Guinea, and N. M. R. Peres, Electronic properties of Graphene multilayers, Phys. Rev. Lett. 97 (2006) 266801.

DOI: 10.1103/physrevlett.97.266801

[8] L. A. Falkovsky and A. A. Varlamov, Space-time dispersion of graphene conductivity, Eur. Phys. J. B 56 (2007) 281.

DOI: 10.1140/epjb/e2007-00142-3

[9] L. Z. Zhe, Coulomb Screening and Plasmon Excitation in Graphene at Finite Temperature, Commun. Theor. Phys. 52 (2009) 361.

DOI: 10.1088/0253-6102/52/2/33

[10] R. Sensarma, E. H. Hwang and S. D. Sarma, Dynamic screening and low-energy collective modes in bilayer graphene, Phys. Rev. B 82 (2010) 195428.

DOI: 10.1103/physrevb.82.195428

[11] G. Borghi, M. Polini, R. Asgari and A. H. MacDonald, Dynamical response functions and collective modes of bilayer graphene, Phys. Rev. B 80 (2009) 241402 R.

DOI: 10.1103/physrevb.80.241402

[12] X. F. Wang and T. Chakraborty, Coulomb screening and collective excitations in a graphene bilayer, Phys. Rev. B 75 (2007) 041404 R.

[13] X. F. Wang and T. Chakraborty, Coulomb screening and collective excitations in biased bilayer graphene, Phys. Rev. B 81 (2010) 081402 R.

DOI: 10.1103/physrevb.81.081402

[14] W. L. You and X. F. Wang, Dynamic screening and plasmon spectrum in bilayer graphe, Nanotechnology 23 (2012) 505204.

DOI: 10.1088/0957-4484/23/50/505204

[15] D. K. Patel, S. S. Z. Ashraf and A. C. Sharma, Finite temperature dynamical polarization and plasmons in gapped graphene, Phys. Status Solidi B 252 (2015) 1817.

DOI: 10.1002/pssb.201451682

[16] P. K. Pyatkovskiy, Dynamical polarization, screening, and plasmons in gapped graphene, J. Phys. Condens. Matter 21 (2009) 025506.

DOI: 10.1088/0953-8984/21/2/025506

[17] A. Qaiumzadeh and R. Asgari, The effect of sublattice symmetry breaking on the electronic properties of a doped graphene, New. J. Phys 11 (2009) 095023.

DOI: 10.1088/1367-2630/11/9/095023

[18] L. A. Falkovsky and S. S. Pershoguba, Optical far-infrared properties of a graphene monolayer and multilayer, Phys. Rev. B 76 (2007) 153410.

DOI: 10.1103/physrevb.76.153410

[19] I. Gierz, C. Riedl, U. Starke, C. R. Ast, and K. Kern, Atomic Hole Doping of Graphene, Nano Lett. 8 (2008) 4603.

DOI: 10.1021/nl802996s

[20] D. A. Siegel, S. Y. Zhou, F. E. Gabaly, A. V. Fedorov, A. K. Schmid, and A. Lanzara, Self-doping effects in epitaxially grown graphene, Appl. Phys. Lett. 93 (2008) 243119.

DOI: 10.1063/1.3028015

[21] S. Y. Zhou, D. A. Siegel, A. V. Fedorov, and A. Lanzara, Physica E 40 2642 (2008).

[22] G. Giovannetti, P. A. Khomyako, G. Brocks, P. J. Kelly, and J. Van den Brink, Phys. Rev. B 76 073103 (2007).

[23] D. K. Patel, A. C. Sharma and S. S. Z. Ashraf, Temperature dependent screened electronic transport in gapped graphene, Phys. Status Solidi B 252 (2015) 282.

DOI: 10.1002/pssb.201451040

[24] A. C. Sharma and A. Bajpai, Dynamical conductivity of low-dimensional systems, J. Mod. Phys. B 16 (2002) 151.