Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 21: Optical Properties 1
HL 21.12: Talk
Wednesday, September 7, 2022, 18:15–18:30, H32
Fröhlich polarons in cubic materials — •B. Guster1, P.M.M.C. Melo2, B.A.A. Martin3, V. Brousseau-Couture4, J.C. de Abreu2, A. Miglio1, M. Giantomassi1, M. Côté4, J.M. Frost3, M.J. Verstraete2, and X. Gonze1,5 — 1UCLouvain(UCL), IMCN, Louvain-la-Neuve, Belgium — 2NanoMat/Q-Mat/CESAM, Université de Liège, Liège, Belgium — 3Department of Physics, Imperial College London, London, UK — 4Département de Physique, Université de Montréal, Montréal, Canada — 5Moscow, Russia
Most works on polaron models, to understand their characteristics such as radius, effective mass, mobility and energy dispersion, have focused on the original Fröhlich model. Real cubic materials have electronic band extrema that are often degenerate, or anisotropic. In this work, we keep the continuum hypothesis inherent to large polaron models, but go beyond the existing isotropic and nondegeneracy hypotheses, and also include multiple phonon modes. For polaron effective masses, we provide (i) the analytical result for the case of anisotropic electronic energy dispersion, with two distinctive effective masses (uniaxial), (ii) an approximate expression for the case of three distinctive axes (ellipsoidal), (iii) numerical simulations for the 3-band degenerate case, typical of III-V and II-VI semiconductor valence bands. We also deal with the strong-coupling limit, using a variational treatment: we propose trial wavefunctions for the three above-mentioned cases as well, providing polaron radii and energies. We gauge such approaches for the case of a dozen of II-VI and III-V semiconductors, and oxides.