Laser induced effects on the electronic and transport properties of graphene

PABLO M. PÉREZ PISKUNOW; H. L. CALVO; S. ROCHE; L. E. F. FOA TORRES; GONZALO USAJ; CARLOS A. BALSEIRO

Chemnitz

Congreso; Graphene Week 2013; 2013

TU Chemnitz

While lasers are powerful characterization tools for carbon-based nanodevices, they can also provide meansof controlling their electrical response. Recent studies hint that laser-illumination can be used to open themuch sought-for bandgaps in graphene [1]. Floquet theory applied to realistic models of these nanostructuresunveils this captivating non-perturbative effect as a lifting of degeneracies in the so-called Floquet space [2].In this presentation, we discuss two facets of this problem.The first is the interplay between lateral confinement and photon-induced non-adiabatic processes on theelectronic properties of laser-illuminated graphene nanoribbons. A strong dependence on the polarizationdirection for small ribbons is predicted [3]. Depending on the device setup (edges geometries, ribbon width,polarization direction and metallic/semiconducting character of the sample), a laser with frequency Ω mayeither not affect the electronic structure, or induce bandgaps or depletions at ħΩ/2, and/or at other energiesnot commensurate with half the photon energy. Similar features are also observed in the dc conductance,suggesting the use of the polarization direction to switch on and off the graphene device.The second facet is the generation of laser-induced protected states as predicted in [4-6]. Here, we re-examine the nature of these states, their contribution to the conductance and their robustness against disorder[7]. Our results could guide the design of novel types of optoelectronic nano-devices.References:[1] T. Oka and H. Aoki, Phys. Rev. B 79, 081406R (2009); S. V. Syzranov, M. V. Fistul, and K. B. Efetov,Phys. Rev. B 78 (2008) 045407[2] H. L. Calvo, H. M. Pastawski, S. Roche, and L. E. F. Foa Torres, Appl. Phys. Lett. 98 (2011) 232103.[3] H. L. Calvo, P. M. Perez-Piskunow, S. Roche, and L. E. F. Foa Torres, Appl. Phys. Lett. 101 (2012)253506.[4] T. Kitagawa, T. Oka, A. Brataas, L. Fu, and E. Demler, Phys. Rev. B 84 (2011) 235108.[5] Z. Gu, H. A. Fertig, D. P. Arovas, and A. Auerbach, Phys. Rev. Lett. 107 (2011) 216601.[6] E. Suarez Morell and L. E. F. Foa Torres, Phys. Rev. B 86 (2012) 125449.[7] P. M. Perez-Piskunow, G. Usaj, C. A. Balseiro, L. E. F. Foa Torres, unpublished