Magnetic-order-induced band splitting in the thermomodulation spectra of the ferromagnetic semiconductor CdCr2Se4

Stoyanov, S. G.; Iliev, M. N.; Stoyanova, S.

doi:10.1002/pssa.2210300113

Cited by 25 publications

References 26 publications

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A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

Aers

Boardman

Isaac

1976

Phys. Stat. Sol. (a)

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A Monte Carlo method which avoids the usual approximate Boltzmann equation approach is used to calculate the electronic properties of ferromagnetic, non‐degenerate, n‐type CdCr2Se4 as a function of applied electric field strength. Full account is taken of the dispersion of the magnon system and results for the velocity–field characteristic, the mean energy, and the subband population fraction are given in graphical form. The character of the interband electron–magnon scattering rates are examined in some detail and the nature of the negative differential conductivity n.d.c. is discussed. It is shown that n.d.c. sets in (for m* = 0.1m0) at 4 kV/cm and that a peak velocity of 2.3 × 107 cm/s is achieved. These values are much more compatible with what is expected for a Gunn effect material than the previously published results which were derived from a displaced Maxwellian approximation coupled with the unrealistic assumption of a non‐dispersive magnon system.

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A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

Aers

Boardman

Isaac

1976

Phys. Stat. Sol. (a)

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Fine structure of the reflectivity maximum of CdCr2Se4 single crystals

Zvára

Родэ

Bok

et al. 1980

Phys. Stat. Sol. (a)

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on the occasion of his 75th birthday 1)Wavelength modulation as a derivative method is very sensitive to a weak structure in the spectrum. Wavelength-modulated (WM) specular reflectivity of CdCr2Se4 single crystals has been measured in the spectral region E = 1 . 3 to 2.7 eV. A detailed investigation of this absorption region is important owing to determination of the fundamental electronic transitions. The modulation of the wavelength of the incident light has been accomplished by vibrating a quartz plate placed in front of the exit slit of a C a r l Zeiss SPM 1 monochromator. As light detector, either an EMI 9558 QB photomultiplier o r an EG-d G HW-4000B silicon photovoltaic photodiode have been used in the appropriate spectral region. Measuring with a photomultiplier, the dc component of the anode current has been kept constant by means of a simple stabilizer and by dynode chain voltage regulation. The ac signal detected by a'lock-in amplifier was then proportional to the relative change of reflectivity A R / R and it was directly registered by H P 9603A measurement and control system. The true relative reflectivity change AR/R of the sample has been calculated from the difference between the modulated signal reflected from the sample and that reflected from the aluminium reference m i r r o r . The samples were ground and poliSed from single crystals grown from the melt /l/. Typical results of the WM reflection meas-I I I I I Fig. 1. Wavelength-modulated reflectivity 11 I( 16 16 20 21 24 26 spectra of CdCrZSeq single c r y s t a l s a t 293 K I L (evI -(broken line) and 78K (full line), respectivelyly 1) K e Karlovu 5, 12116 Prague 2, CSSR.

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Raman scattering of HgCr₂Se₄

Iliev

Anastassakis

Arai

1978

Physica Status Solidi (b)

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ILIEV~) (a), E. ANASTASSAKIS~) (a), and T. ARAI (b)The Raman spectrum of the ferromagnetic semiconductor HgCr,Se, (To = 106 K) and its dependence on temperature and incident photon energy is measured. Five Raman-active modes are found at 65, 157, 168, 210, and 237 cm-l and are assigned to certain ionic vibrations in the spinel unit cell. The temperature variations of the scattering cross-section for different modes show no pronounced anomalies near the magnetic phase transition at TC but depend significantly on the wavelength of the exciting radiation. The resonance curve at 300 K exhibits two peaks a t 1.9 and 2.35 eV superimposed by a broad structure which increases toward low energies. E l a~e p e~ cnehip K O M~A H~~A O H H O~O paccemm cBeTa (KPC) (PeppoMarnmHoro nony-IIpOBOnHkIKa HgCr,Se, (Tc = 106 K) II er0 3aBHCHMOCTb OT TeMIIepaTypbI EI 3HeprEIEI (POTOHOB ~oa6ymnaro1uero CBeTa. HOJIOCbI C0OTBeTCTBYH)WIIe (POHOHBM, PKTHBHbIM B KPC, paCnOJlOmeHbI IIpH 65, 157, 168, 210 II 237 em-'. HpABaR TeMnepaTypHbIX H3MeHeHAfi AHTeHCIIBHOCTIl HPc He IIpOJlBJlfleT aH0ManHfi B6nH3H MarHHTHOrO @a3OBOrO IIepeXOna B T O W W HIoPH Tc, HO 3aBIICAT CyIseCTBeHHO OT 3HeprllH ~036ymna1orrr~x (POTOHOB.Pe30-HancHaR Kpmaa n n~ 300 K HMeeT m a n m a n p~ 1,9 M 2,35 eV II ~o a p a c~a e~ c nomime-HHeM (POTOHHOZ~ 3~e p r m .

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Magnetic-order-induced band splitting in the thermomodulation spectra of the ferromagnetic semiconductor CdCr2Se4

Cited by 25 publications

References 26 publications

A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

Fine structure of the reflectivity maximum of CdCr2Se4 single crystals

Raman scattering of HgCr₂Se₄

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Magnetic-order-induced band splitting in the thermomodulation spectra of the ferromagnetic semiconductor CdCr2Se4

Cited by 25 publications

References 26 publications

A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

A Monte Carlo study of the gunn effect behaviour of a ferromagnetic semiconductor

Fine structure of the reflectivity maximum of CdCr2Se4 single crystals

Raman scattering of HgCr2Se4

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Product

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Raman scattering of HgCr₂Se₄