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Magneto‐optical spectroscopy of (Zn,Co)O epilayers
Author(s) -
Pacuski W.,
Ferrand D.,
Cibert J.,
Deparis C.,
Kossacki P.,
Morhain C.
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200564754
Subject(s) - zeeman effect , exciton , magnetic circular dichroism , photoluminescence , cobalt , chemistry , condensed matter physics , ionic bonding , spectroscopy , magnetization , paramagnetism , spins , ion , materials science , physics , spectral line , inorganic chemistry , magnetic field , optoelectronics , organic chemistry , quantum mechanics , astronomy
We present a magneto‐optical study of (Zn,Co)O layers grown by molecular beam epitaxy. We observed sharp lines related to 4 A 2 – 2 E intra‐ionic Co 2+ transitions, and to the A , B and C excitons. Intra‐ionic transitions observed by absorption and photoluminescence were used to determine the values of the parameters describing the isolated Co ions, such as the easy‐plane magnetic anisotropy and the g ‐factor of the S = 3/2 Cobalt spin. Excitonic transitions observed in reflectivity were used to determine the giant Zeeman splitting and to estimate the effective coupling 〈 N 0 ( α – β )〉 A , B = 0.4 eV between excitons and Cobalt spins. Due to the electron–hole exchange within the exciton, this effective spin–exciton coupling is much weaker than the exchange integrals for free carriers, estimated to be N 0 | α – β | ≈ 0.8 eV, with a positive value of ( α – β ) if the normal ordering of the valence band of ZnO is assumed. The Zeeman splitting of diluted samples and the magnetic circular dichroism (for a higher Co content) are proportional to the magnetization of the paramagnetic, isolated Cobalt ions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)