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arXiv · 1601.02663

Damping of Landau levels in neutral graphene at low magnetic fields: A phonon Raman scattering study

F. M. Ardito·T. G. Mendes-de-Sa·A. R. Cadore·P. F. Gomes·D. L. Mafra·I. D. Barcelos·R. G. Lacerda·F. Iikawa·E. Granado
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Abstract

Landau level broadening mechanisms in electrically neutral and quasineutral graphene were investigated through micro-magneto-Raman experiments in three different samples, namely, a natural single-layer graphene flake and a back-gated single-layer device, both deposited over Si/SiO2 substrates, and a multilayer epitaxial graphene employed as a reference sample. Interband Landau level transition widths were estimated through a quantitative analysis of the magnetophonon resonances associated with optically active Landau level transitions crossing the energy of the E_2g Raman-active phonon. Contrary to multilayer graphene, the single-layer graphene samples show a strong damping of the low-field resonances, consistent with an additional broadening contribution of the Landau level energies arising from a random strain field. This extra contribution is properly quantified in terms of a pseudomagnetic field distribution Delta_B = 1.0-1.7 T in our single-layer samples.

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F. M. Ardito, T. G. Mendes-de-Sa, A. R. Cadore, P. F. Gomes, D. L. Mafra, I. D. Barcelos, R. G. Lacerda, F. Iikawa, E. Granado. 2018-01-16. Damping of Landau levels in neutral graphene at low magnetic fields: A phonon Raman scattering study. https://doi.org/10.1103/physrevb.97.035419

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