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Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

Texto completo
Henriques, A. B. [1] ; Moraes, F. C. D. [1] ; Galgano, G. D. [1] ; Meaney, A. J. [2] ; Christianen, P. C. M. [2] ; Maan, J. C. [2] ; Abramof, E. [3] ; Rappl, P. H. O. [3]
Número total de Autores: 8
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil
[2] Radboud Univ Nijmegen, Inst Mol & Mat, High Field Magnet Lab, NL-6525 ED Nijmegen - Netherlands
[3] INPE, LAS, BR-12227010 Sao Jose Dos Campos - Brazil
Número total de Afiliações: 3
Tipo de documento: Artigo Científico
Fonte: Physical Review B; v. 90, n. 16 OCT 9 2014.
Citações Web of Science: 4
Assunto(s):Semicondutores   Luminescência   Campo magnético

The recent discovery of a polaron-associated zero phonon line in the band-edge photoluminescence of high optical quality EuTe crystals opens up the prospect of answering long-standing questions about the polaron internal structure, thermal stability, and generation efficiency. Here, a Schrodinger equation for the polaron was formulated and resolved by using both variational and self-consistent methods. The theory is in good agreement with measurements of the zero phonon line as a function of magnetic field and temperature, and it could be applied to other polaronic systems. It is deduced that, in EuTe, at 0 K, a polaron carries a magnetic moment of 610 mu(B), and its binding energy is 27 meV. However, this binding energy does not carry the usual meaning of thermal stability, because it decreases drastically when the sample is warmed up. For instance, at T = 100 K, the binding energy is already reduced to only 6 meV. The thermal destruction of a polaron is brought about by thermal fluctuations of the spin lattice that suppress the electron's self-energy. Photoluminescence excitation spectra of EuTe demonstrate that the photogeneration of polarons becomes increasingly inefficient when the energy of the pumping photon is increased above the band gap. (AU)

Processo FAPESP: 12/23406-0 - Investigação óptica de sistemas spintrônicos
Beneficiário:Andre Bohomoletz Henriques
Linha de fomento: Auxílio à Pesquisa - Regular