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Band structure evolution and the origin of magnetism in (Ga,Mn)As: From paramagnetic through superparamagnetic to ferromagnetic phase

L. Gluba, O. Yastrubchak, J. Z. Domagala, R. Jakiela, T. Andrearczyk, J. Żuk, T. Wosinski, J. Sadowski, and M. Sawicki
Phys. Rev. B 97, 115201 – Published 13 March 2018
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Abstract

The high-spectral-resolution optical studies of the energy gap evolution, supplemented with electronic, magnetic, and structural characterization, show that the modification of the GaAs valence band caused by Mn incorporation occurs already for a very low Mn content, much lower than that required to support ferromagnetic spin–spin coupling in (Ga,Mn)As. Only for n-type (Ga,Mn)As with the Mn content below about 0.3% the Mn-related extended states are visible as a feature detached from the valence-band edge and partly occupied with electrons. The combined magnetic and low-temperature photoreflectance studies presented here indicate that the paramagnetic ↔ ferromagnetic transformation in p-type (Ga,Mn)As takes place without imposing changes of the unitary character of the valence band with the Fermi level located therein. The whole process is rooted in the nanoscale fluctuations of the local (hole) density of states and the formation of a superparamagnetic-like state. The Fermi level in (Ga,Mn)As is coarsened by the carrier concentration of the itinerant valence band holes and further fine-tuned by the many-body interactions.

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  • Received 21 November 2017

DOI:https://doi.org/10.1103/PhysRevB.97.115201

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

L. Gluba1,2, O. Yastrubchak3,2,*, J. Z. Domagala4, R. Jakiela4, T. Andrearczyk4, J. Żuk2, T. Wosinski4, J. Sadowski5,4,6, and M. Sawicki4

  • 1Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
  • 2Institute of Physics, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland
  • 3V.E. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
  • 4Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
  • 5MAX-IV laboratory, Lund University, P.O. Box. 118, 22100 Lund, Sweden
  • 6Department of Physics and Electrical Engineering, Linnaeus University, SE-391 82 Kalmar, Sweden

  • *plazmonoki@gmail.com

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Issue

Vol. 97, Iss. 11 — 15 March 2018

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