FIR absorption of Zn1−xCrxS

Mac, W.; Twardowski, A.; Boonman, M.E.J.; Wittlin, A.; Krevet, R.; Ortenberg, M. von; Demianiuk, M.

doi:10.1016/0921-4526(94)01070-h

Cited by 12 publications

(7 citation statements)

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“…The field dependence of the energy level spectra is quite well described by a simple crystal field model ( Fig. 2) [13,14].…”

Section: Cr Ion Energy Structurementioning

confidence: 93%

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Cr-Based II-VI Semimagnetic Semiconductors

Twardowski

1995

Acta Phys. Pol. A

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We review the magnetic and optical properties of recently grown Cr--based II-VI semimagnetic semiconductors. We focus on two features of these materials which distinguish them from other semimagnetic semiconductors: the particular magnetic behaviour of these crystals, resulting from the Cr " ion energy structure determined by a strong, static Jahn-Teller effect, and a ferromagnetic p-d exchange interaction, which is unique for II-VI semimagnetic semiconductors.

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“…The field dependence of the energy level spectra is quite well described by a simple crystal field model ( Fig. 2) [13,14].…”

Section: Cr Ion Energy Structurementioning

confidence: 93%

“…Recently far infrared laser experiments were performed for ZnCrSe [13] and ZnCrS [14] at high magnetic fields. The characteristic transitions for different Cr centres are well visible.…”

Section: Cr Ion Energy Structurementioning

confidence: 99%

Cr-Based II-VI Semimagnetic Semiconductors

Twardowski

1995

Acta Phys. Pol. A

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“…In the first case the anisotropy of a single ion may lead to the huge anisotropy in the macroscopic magnetization. We recall that the presence of differently distorted types of centers have been observed for Cr++ for which tetragonal Jahn-Teller distortion occurs [5]. However, in this case the hexagonal stress is at the same angle to all of the Jahn-Teller distortion axes and no centers are favored.…”

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confidence: 99%

Magnetic Anisotropy of V⁺⁺in CdS

et al. 1996

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The magnetization measurements at magnetic field up to 6 Τ obtained from newly grown hexagonal Cd1-x Vx S (x 0.0004) are presented. The strong anisotropy of magnetization is observed at low temperatures (1.6 < Τ < 20 K). The data are welł described by the crystal field model calculations taking into account static trigonal Jahn-Teller distortion and spin-orbit coupling. The strong s, p-d exchange interaction is one of the most characteristic features of diluted magnetic semiconduction (DMS) [1]. DMS based on transition metal (TM) ions with less than half fllled d shell are particularly interesting for a possible ferromagnetic p-d exchange. So far, among all the studied II-VI systems, only the chromium based crystals revealed ferromagnetic p-d exchange [2] (Cr++ electronic configuration is d4). The recent growth of CdS heavily doped with vanadium calls for examining the situation in DMS with V++ ions (electronic configuration is d3).. Since the information about spin alignment is indispensable for understanding exchange interaction we thought it is worthwhile to study magnetization of this new material.The ground term of the V++ (d3 ) ion is 4F, which means that the total spin momentum of the ion is S = 3/2 and total orbital momentum is L = 3. The cubic crystal fleld splits this 7-fold orbitally degenerate term into two orbital triplets: 4 Τ1 and 4 Τ2 and an orbital singlet 4Α2 (see Fig. la). The ground orbital triplet 4 Τ1 undergoes static Jahn-Teller distortion of trigonal symmetry [3,4] yielding further splittings. Thus in the cubic symmetry there exist four equivalent possible distortion axes corresponding to one of the (111) crystal axes and four different kinds of centers are expected. In wurtzite structure, the hexagonal crystal field may be regarded as a trigonally distorted (along c axis) cubic field. In this case one of the Jahn-Teller distortion axes coincide with the hexagonal stress direction. This way the degeneracy of the four V center types is lifted. If the energy of the center •Τ1 is work was partially supported by the Committee for Scientific Research (Poland).(809)

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“…The order of these low lying energy levels for Ζn1-xCrxTe is essentially different to that for Zn1-x Crx S or Zn1-x Crx Se. The reason for this reversed order of the zero field energy levels is a strong covalency effect present in ZnTe [8]. Therefore, different spin-orbit interaction parameters were introduced for the t and e orbital symmetries.…”

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“…To describe the data we used a simple crystal field model proposed by Vallin et al [5], also used for ZnSe [3,6] and ZnS [7]. The Hamiltonian for d electrons of the Cr++ ion can be written as .…”

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High-Field EPR of Zn_1-xCr_xTe

et al. 1995

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High magnetic field electron paramagnetic resonance experiments have been performed on Ζn1-xCrxTe covering the energy range 1-7 cm -1 in fields up to 20 T at T = 1.2 K. The static magnetic field was oriented along the (100), (110) and (111) crystallographic axes of the sample. Pronounced absorptioii lines for intra-chromium transitions have been observed for these different orientations, revealing a strong anisotropy due to a static Jahn-Teller distortion. The measured low energy level structure of the C r ++ ion can be described by a cubic crystal field model including this distortion of the Cr centers.PACS numbers: 75.50. Ppa, 76.30.Fc, 78.30.Fs Diluted magnetic semiconduction (DMS) or semimagnetic semiconduction (SMSC) are semiconductors (mostly II-VI) where a controlled fraction of the cations is randomly substituted by magnetic ions [1]. On the contrary to the well-known Mn, Fe and Co based DMS, the Cr based DMS are the first SMSC known so far with a ferromagnetic p-d exchange between the two coexisting electronic subsystems, the localized d-electrons of the Cr++ ion and the ZnTe band electrons [2]. From the magnetic point of view the Cr-SMSC have an intermediate character between that of a Brillouin-type paramagnet and a Van Vleck-type system. Moreover the Cr++ center in a tetrahedral crystal field undergoes a static Jahn-Teller distortion along one of the (100) axes of the crystal, which results in the existence of three types of nonequivalent Cr++ centers. This leads to pronounced anisotropy of the Cr++ ion energy level stucture and magnetic properties [3].To understand the low temperature magnetic properties of Zn1-x Crx Te, we need to know the exact low energy level stucture of the Cr++ ion. This energy diagram consists of five closely lying energy levels in the energy range between 0 and 8 cm -1 (ΔΕ N kBT, T = 4.2 K), with a complicated magnetic field dependence. A standard EPR setup typically operates at one fixed frequency between (829)

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FIR absorption of Zn1−xCrxS

Cited by 12 publications

References 6 publications

Cr-Based II-VI Semimagnetic Semiconductors

Cr-Based II-VI Semimagnetic Semiconductors

Magnetic Anisotropy of V⁺⁺in CdS

High-Field EPR of Zn_1-xCr_xTe

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FIR absorption of Zn1−xCrxS

Cited by 12 publications

References 6 publications

Cr-Based II-VI Semimagnetic Semiconductors

Cr-Based II-VI Semimagnetic Semiconductors

Magnetic Anisotropy of V++in CdS

High-Field EPR of Zn1-xCrxTe

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Resources

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Magnetic Anisotropy of V⁺⁺in CdS

High-Field EPR of Zn_1-xCr_xTe