Electronic structure of FeCr2S4and Fe0.5Cu0.5Cr2S4

Kurmaev, E.Z.; Postnikov, A. V.; Palmer, Helen; Greaves, C.; Bartkowski, S.; Tsurkan, V.; Demeter, M.; Hartmann, D.; Neumann, M.; Zatsepin, D. A.; Galakhov, V. R.; Shamin, S. N.; Trofimova, V. A.

doi:10.1088/0953-8984/12/25/306

Cited by 17 publications

(26 citation statements)

References 25 publications

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“…Details of the sample preparation are de-scribed elsewhere. 17 No indication for the existence of secondary phases was found by x-ray diffraction analysis of powdered single crystals. X-ray single-crystal analysis confirmed the high structural homogeneity of the samples.…”

Section: Methodsmentioning

confidence: 99%

“…12 In addition, solid solutions of the ferrimagnetic semiconductor FeCr 2 S 4 and the metallic ferromagnet CuCr 2 S 4 show a number of puzzling properties: From the very beginning, a controversial discussion has been arising whether the Cu ions are mono-or divalent for x ≥ 0.5. 15,16,17 For x < 0.5 it was established that only monovalent and hence diamagnetic (d 10 ) Cu exists in the mixed crystals. 18 Moreover, Fe 1−x Cu x Cr 2 S 4 shows two metal-to-insulator transitions as a function of x, as the room-temperature resistivity reveals two minima at x = 0.2 and x = 1 and concomitantly the Seebeck coefficient changes sign two times.…”

Section: 14mentioning

confidence: 99%

“…15,19 Additionally, bandstructure calculations predicted that the Fe 1−x Cu x Cr 2 S 4 system should exhibit a half-metallic nature. 17,20,21 Recent experimental investigations of Fe 1−x Cu x Cr 2 S 4 single crystals indicated a strong dependence of their magnetic and magneto-transport properties on hydrostatic pressure suggesting a strong magneto-elastic coupling. 22,23 Measurements on the ac susceptibility in pure FeCr 2 S 4 exhibited a cusp in the low-field magnetization and the onset of magnetic irreversibilities at 60 K was explained by domain-reorientation processes.…”

Section: 14mentioning

confidence: 99%

“…5 can be compared with band-structure calculations of these compounds. 17,21,39 Local spin-density approximation (LSDA) band-structure calculations predict a halfmetallic ground state of FeCr 2 S 4 , with a partly filled e band at the Fermi level. Correlation effects via LSDA+U yield a splitting of the Fe e band into a lower and upper Hubbard band characterizing FeCr 2 S 4 as a MottHubbard insulator.…”

Section: B Dynamic Conductivity and Electronic Excitationsmentioning

confidence: 99%

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Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
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A detailed investigation of phonon excitations and charge carrier dynamics in single crystals of Fe1−xCuxCr2S4 (x = 0, 0.2, 0.4, 0.5) has been performed by using infrared spectroscopy. In FeCr2S4 the phonon eigenmodes are strongly affected by the onset of magnetic order. Despite enhanced screening effects, a continuous evolution of the phonon excitations can be observed in the doped compounds with x = 0.2 (metallic) and x = 0.4, 0.5 (bad metals), but the effect of magnetic ordering on the phonons is strongly reduced compared to x = 0. The Drude-like charge-carrier contribution to the optical conductivity in the doped samples indicates that the colossal magneto-resistance effect results from the suppression of spin-disorder scattering.

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Section: Methodsmentioning

confidence: 99%

Section: 14mentioning

confidence: 99%

Section: 14mentioning

confidence: 99%

Section: B Dynamic Conductivity and Electronic Excitationsmentioning

confidence: 99%

See 2 more Smart Citations

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
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“…In this case, V and Mn have antiferromagnetically aligned magnetic moments that exactly cancel each other. To date, there has been no successful experimental realization of the HM-AFM.The thiospinel FeCr 2 S 4 in its metallic phase has the HM ferrimagnetic state with nominal valence configurations of Fe 2+ (d 6 ) and Cr 3+ (d 3 ) [5][6][7]. The magnetic moments of Fe and Cr are 4µ B and −3µ B , respectively, which produce the integer total magnetic moment of −2µ B per formula unit.…”

mentioning

confidence: 99%

Half-metallic antiferromagnets in thiospinels

2001

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We have theoretically designed the half-metallic (HM) antiferromagnets (AFMs) in thiospinel systems, Mn(CrV)S4 and Fe0.5Cu0.5(V0.5Ti1.5)S4, based on the electronic structure studies in the local-spin-density approximation (LSDA). We have also explored electronic and magnetic properties of parent spinel compounds of the above systems; CuV2S4 and CuTi2S4 are found to be HM ferromagnets in their cubic spinel structures, while MnCr2S4 is a ferrimagnetic insulator. We have discussed the feasibility of material synthesis of HM-AFM thiospinel systems.PACS numbers: 71.20. Be, 75.25.+Z, 75.50.Ee Since the first theoretical report of Heusler halfmetallic (HM) ferromagnet NiMnSb by de Groot et al.[1], much effort has been devoted to developing the HM magnetic materials, in which the conduction electrons at the Fermi level E F are 100% spin-polarized [2]. Especially, the HM antiferromagnet (AFM) attracts great attention because it is a non-magnetic metal but its conduction electrons are 100% spin-polarized. It can be used as a probe of the spin-polarized scanning tunneling microscope without perturbing the spin-character of samples. Further, the HM-AFM is expected to play a vital role in the future spintronic devices that utilize the spin polarization of the carriers.The first HM-AFM, V 7 MnFe 8 Sb 7 In, which is a derivative of the Heusler compound, was proposed by van Leuken and de Groot [3]. Anther possibility was suggested by Pickett [4] in the double perovskite system such as La 2 VMnO 6 . In this case, V and Mn have antiferromagnetically aligned magnetic moments that exactly cancel each other. To date, there has been no successful experimental realization of the HM-AFM.The thiospinel FeCr 2 S 4 in its metallic phase has the HM ferrimagnetic state with nominal valence configurations of Fe 2+ (d 6 ) and Cr 3+ (d 3 ) [5][6][7]. The magnetic moments of Fe and Cr are 4µ B and −3µ B , respectively, which produce the integer total magnetic moment of −2µ B per formula unit. From this, one can expect that FeV 2 S 4 becomes a HM-AFM, since V has one less electron than Cr and so the magnetic moment of two V 3+ (d 2 : S=1) ions would cancel that of Fe 2+ (d 6 : S=2), still possessing the HM property. Indeed the local-spindensity approximation (LSDA) band calculation yields the HM-AFM electronic structure of FeV 2 S 4 [8]. Unfortunately, FeV 2 S 4 does not exist in the cubic spinel structure but in the hexagonal NiAs structure (Cr 3 S 4 -type) with a complicated magnetic configuration [9]. So the above expectation does not work for FeV 2 S 4 in nature.Motivated by the above expectation, we attempt to search for the HM-AFM in other thiospinel compounds. Most of the thiospinel compounds of AB 2 S 4 -type (A, B: transition metals) with cubic structure have a ferrimagnetic ground state. Usually, the magnetic moment of the A ion in the tetrahedral site is antiferromagnetically polarized with that of the B ion in the octahedral site. Under this circumstance, there are some pairs of A and B which give rise to the exactly cancelled ma...

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Reinvestigation of the Fe, Cu and Cr valences in (FeCu)Cr₂S₄ spinels

Taubitz¹,

Kuepper²,

Raekers³

et al. 2009

Physica Status Solidi (b)

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The valence states of Fe, Cu, and Cr ions in single crystalline Fe1–x Cux Cr2S4 have been studied using X‐ray photoelectron spectroscopy (XPS), X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD). XPS measurements of compositions x = 0.2, 0.5, 0.6, and 0.9 indicate that the Cu and Cr ions remain mainly in the same valence state over the whole substitution range. XAS, XPS and XMCD investigations of Fe0.5Cu0.5Cr2S4 reveal a sample and preparation dependence of the Cu and Fe spectra. The comparison of the Cu 2p XAS spectrum with a literature measurement shows a change in the amount of Cu2+ explained by the appearance of an additional Cu2+ phase, possibly due to oxidation on the surface. XAS, XPS and XMCD spectra of Fe show a Fe3+ impurity phase present in air‐treated Fe0.5Cu0.5Cr2S4, especially in powdered samples. The lines related to trivalent Fe are found to disappear completely after cleaning the samples in‐situ and only the lines attributed to divalent Fe remain. Since many experimental methods rely on powdered samples and measure in air or in low vacuum, these findings provide an explanation for the differing results concerning the Fe valence obtained by these methods. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Electronic structure of FeCr₂S₄and Fe_0.5Cu_0.5Cr₂S₄

Cited by 17 publications

References 25 publications

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Half-metallic antiferromagnets in thiospinels

Reinvestigation of the Fe, Cu and Cr valences in (FeCu)Cr₂S₄ spinels

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Electronic structure of FeCr2S4and Fe0.5Cu0.5Cr2S4

Cited by 17 publications

References 25 publications

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4Rudolf1, Pucher2, Mayr3 et al. 2005Phys. Rev. B16190View full textAdd to dashboardCite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4Rudolf1, Pucher2, Mayr3 et al. 2005Phys. Rev. B16190View full textAdd to dashboardCite

Half-metallic antiferromagnets in thiospinels

Reinvestigation of the Fe, Cu and Cr valences in (FeCu)Cr2S4 spinels

Contact Info

Product

Resources

About

Electronic structure of FeCr₂S₄and Fe_0.5Cu_0.5Cr₂S₄

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Phonon anomalies and charge dynamics inFe1−xCuxCr2S4
Rudolf
¹
,
Pucher
²
,
Mayr
³

et al. 2005
Phys. Rev. B
16
1
9
0
View full text Add to dashboard Cite

Reinvestigation of the Fe, Cu and Cr valences in (FeCu)Cr₂S₄ spinels