Speaker
Alexey Kuzmenko
(University of Geneva)
Description
A.B. Kuzmenko, I. Crassee, J. Levallois, and D. van der Marel
DPMC, University of Geneva,
Quai Ernest Ansermet 24, 1211 Geneva 4, Switzerland
Graphene attracts a lot of attention as a novel optical and plasmonic material. Its optical response is exceptionally sensitive to a magnetic field due to the small cyclotron mass of the Dirac-like charge carriers. This does not only make magneto-optics a useful tool to study this material but also gives rise to giant magneto-optical effects, potentially useful for terahertz applications. In this talk, I’ll overview our magneto-optical studies of large-scale single- and multilayer graphene grown epitaxially on the Si- and C-faces of silicon carbide respectively [1,2,3]. In the highly doped monolayer graphene we observe a strong Drude peak at zero field and a quasiclassical, field-linear, cyclotron resonance at finite fields, which gives rise to a giant Faraday rotation exceeding 0.1 radians at modest fields [1]. In this type of graphene we also found an unexpectedly strong terahertz plasmonic absorption [3] due to natural defects such as terrace steps in SiC. When a field is applied, the plasmon peak splits in two modes, which is a hallmark of the magnetoplasmon physics found earlier in 2D electron gases in semiconductors [4] and on the surface of liquid helium [5]. In quasineutral twisted multilayer graphene, often regarded as a set of decoupled monolayers, we observe quantum LL transitions with the expected square-root like dependence on magnetic field. However, the optical intensity of these transitions is several times smaller than the Kubo formula predicts and its field dependence is not square-root like, as one would expect in ideal and decoupled monolayers [2]. I’ll contrast this serious discrepancy to our recent magneto-optical Kerr rotation spectroscopy experiments in Bernal stacked graphite [6], where a very good agreement between the experiment and the tight-binding Kubo formula is achieved in a broad range of magnetic fields.
[1] I. Crassee, J. Levallois, A.L. Walter, M. Ostler, A. Bostwick, E. Rotenberg, Th. Seyller, D. van der Marel, and A.B. Kuzmenko, Nature Physics 7, 48 (2011).
[2] I. Crassee, J. Levallois, D. van der Marel, A. L. Walter, Th. Seyller, and A. B. Kuzmenko, Phys. Rev. B 84, 035103 (2011).
[3] I. Crassee et al., submitted.
[4] S.J. Allen, H.L. Stormer, and J.C.M. Hwang. Phys. Rev. B 28, 4875 (1983).
[5] D.B. Mast, A.J. Dahm, and A.L. Fetter, Phys. Rev. Lett. 54, 1706 (1985); D.C. Glatti, E.Y. Andrei, G. Deville, J. Poitrenaud, and F.I.B. Williams, Phys. Rev. Lett. 54, 1710 (1985).
[6] J. Levallois, M.K. Tran, and A.B. Kuzmenko, arXiv: 1110.2754; Solid State Communications, Special Issue on Graphene (2012), DOI: 10.1016/j.ssc.2012.04.036.
Primary author
Alexey Kuzmenko
(University of Geneva)
Co-author
I. Crassee
(University of Geneva)
