Julien Levallois, DPMC, Université de Genève

Jeudi 02 Fevrier, 16h
Amphi Howleck, Esc C, 1ème etage

Decrypting the cyclotron effect in graphite using Kerr
rotation spectroscopy

Julien Levallois
Département de Physique de la Matière Condensée
Université de Genève, CH-1211 Genève 4, Switzerland

In semi-metals such as graphite and bismuth, the cyclotron effects are quite strong. In spite ofnumerous studies appeared after the first observation of the cyclotron effect more than fifty years ago [1], the lineshapes and the intensities of the magneto-optical spectrum of graphite are not satisfactorily explained. We measure the infrared magneto-optical Kerr rotation and reflectivity spectra in graphite up to 7 T, which allows us to distinguish transitions of different
electron/hole symmetry [2]. The experimental spectra are compared to a theoretical model based on a tight-binding Slonczewski-Weiss-McClure band model. Most importantly, the c-axis band dispersion and the trigonal warping are taken into account. We find a very good quantitative agreement between theory and experiment in a broad range of magnetic fields. Surprisingly, it appears that the high-order cyclotron harmonics are optically almost as strong as
the fundamental resonance. Our results show the relevance of considering the real shape and the entire Fermi surface and resolve the longstanding problem of microscopic description of the cyclotron effect in graphite.

[1] J.K. Galt, W.A. Yager and H.W. Dail Jr., Phys. Rev. 103, 1586–1587 (1956)
[2] Julien Levallois, M.K. Tran and Alexey B. Kuzmenko, arXiv:1110.2754v2

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