Coexistence of minority valence Cr2+ and Cr4+ ions in the ternary magnetic semiconductor CdCr2S4

Nikiforov, K. G.; Радауцан, С. И.; Gurevich, A. G.; Emiryan, L. M.

doi:10.1007/bf02457882

Cited by 3 publications

(1 citation statement)

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“…Note, that the lifetime of the excited state of this exciton must be inversely proportional to the giant oscillator strength [18]. According to [37], Se vacancies are predominant among possible defects in Hg 1−x Cd x Cr 2 Se 4 . Due to the anion vacancies the crystal contains many Cr 2+ ions which in combination with selenide vacancy form (ν Se -Cr 2+ ) complexes.…”

Section: Absorption Spectroscopymentioning

confidence: 99%

Static and time-resolved mid-infrared spectroscopy of Hg_0.95Cd_0.05Cr₂Se₄spinel

Barsaume

Telegin

Sukhorukov

et al. 2017

J. Phys.: Condens. Matter

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Static and time-resolved mid-infrared spectroscopy of ferromagnetic single crystal HgCdCrSe was performed below the absorption edge, in order to reveal the origin of the electronic transitions contributing to the magneto-optical properties of this material. The mid-infrared spectroscopy reveals a strong absorption peak around 0.236 eV which formerly was assigned to a transition within the selenide-chromium complexes ([Formula: see text] -Cr). To reveal the sensitivity of the transition to the magnetic order, we performed the studies in a temperature range across the Curie temperature and magnetic fields across the value at which the saturation of ferromagnetic magnetization occurs. Despite the fact that the Curie temperature of this ferromagnetic semiconductor is around 107 K, the intensity of the mid-infrared transition reduces substantially increasing the temperature, so that already at 70 K the absorption peak is hardly visible. Such a dramatic decrease of the oscillator strength is observed simultaneously with the strong red-shift of the absorption edge in the magnetic semiconductor. Employing a time-resolved pump-and-probe technique enabled us to determine the lifetime of the electrons in the excited state of this optical transition. In the temperature range from 7 K to 80 K, the lifetime changes from 3 ps to 6 ps. This behavior agrees with the phenomenon of giant oscillator strength described earlier for weakly bound excitons in nonmagnetic semiconductors.

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Section: Absorption Spectroscopymentioning

confidence: 99%