Valence instabilities of Tm in its compounds and solid solutions

Holtzberg, F.; Penney, T.; Tournier, R.

doi:10.1051/jphyscol:19795108

Cited by 39 publications

(20 citation statements)

References 15 publications

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“…11͒. The opening of such a pseudogap may explain the increasing of the electrical resistivity below the Néel temperature, 18,20,21 as well as an enormous negative magnetoresistivity associated with the metamagnetic transition to the high-field aligned state and decreasing of the Hall coefficient in an external magnetic field. 22 The pinning of a partly occupied 13th f level is different in TmS and TmSe.…”

Section: Tmsementioning

confidence: 99%

“…The resistivity of TmSe shows a Kondo-like logarithmic temperature dependence at high temperatures followed by a sharp increase at T N ϭ3.5 K, which is thought to be a transition into an insulating state. 18,20,21 This anomaly in the vicinity of T N shows a very complicated response to external magnetic fields and to pressure. 17,22 TmTe is a magnetic semiconductor with a localized 13th f level between a filled Te5p valence band and an empty Tm5d conduction band.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure and magneto-optical Kerr effect of Tm monochalcogenides

2001

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The optical and magneto-optical ͑MO͒ spectra of Tm monochalcogenides are investigated theoretically from first principles, using the fully relativistic Dirac linear combination of muffin-tin orbitals band structure method. The electronic structure is obtained with the local-spin-density approximation ͑LSDA͒, as well as with the so-called LSDAϩU approach. In contrast to LSDA, where the stable solution in TmTe is a metal, the LSDAϩU gave an insulating ground state. LSDAϩU theory predicts the thulium ion in TmTe to be in an integer divalent state. It also shows a gradual decreasing of the energy gap with reducing of the lattice constant. LSDAϩU theoretical calculations produce a similar energy band structure in TmS and TmSe, with twelve 4 f bands fully occupied and hybridized with chalcogenide p states. The 14th f hole level was found to be completely unoccupied and well above the Fermi level and a hole 13th f level is partly occupied and pinned at the Fermi level. The occupation number of the 13th f level is equal to 0.12 and 0.27 in TmS and TmSe, respectively ͑valence 2.88ϩ and 2.73ϩ͒. Such an energy band structure of thulium monochalcogenides describes well their measured bremsstrahlung isochromat spectroscopy ͑BIS͒, and x-ray and ultraviolet photoemission spectra as well as the optical and MO spectra. The origin of the Kerr rotation realized in the compounds is examined.

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Section: Tmsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronic structure and magneto-optical Kerr effect of Tm monochalcogenides

2001

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“…However, the situation is so complicated that there is no overall consistent explanation of the physical properties of this compound. The resistivity of TmSe shows a Kondo-like logarithmic temperature dependence at high temperatures followed by a sharp increase at T N = 3.5 K, which is thought to be a transition into an insulating state [47,49,50]. This anomaly in the vicinity of T N shows a very complicated response to external magnetic fields and to pressure [46,51].…”

Section: Tm Monochalcogenidesmentioning

confidence: 99%

“…Through the FM -AFM phase transition a pseudo gap at the Fermi level is opened in both TmS and TmSe (figure 6). The opening of such a pseudo gap may explain the increase of the electrical resistivity below Néel temperature [47,49,50], as well as an enormous negative magnetoresistivity associated with the metamagnetic transition to the high-field aligned state and the decrease of the Hall coefficient in an external magnetic field [51].…”

Section: Tmsementioning

confidence: 99%

Electronic Structure of Mixed Valent Systems

Antonov¹,

Shpak²,

Yaresko³

2004

Condens. Matter Phys.

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The electronic structure of Tm and Sm monochalcogenides, SmB 6 and Yb 4 As 3 is theoretically investigated from the first principles, using the fully relativistic Dirac LMTO band structure method. The electronic structure is obtained using the local spin-density approximation (LSDA), as well as the so-called LSDA+U approach. While the standard LSDA approach is incapable of correctly describing the electronic structure of such materials due to the strong on-site Coulomb repulsion, the LSDA+U approach is remarkably accurate in providing a detailed agreement with experiment for a number of properties.

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“…In TmSe, both the lattice constant and the Curie constant are intermediate between those of divalent and trivalent values [1]. The resistivity of TmSe shows a Kondo-like logarithmic temperature dependence at high temperatures followed by a sharp increase at T N 3.5 K, which is thought to be a transition into an insulating state [5][6][7]. This anomaly in the vicinity of T N shows a very complicated response to external magnetic fields or pressures [8,9].…”

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confidence: 92%

Pressure Induced Semiconductor to Metal Transition in TmTe

Matsumura

Kosaka

Tang³

et al. 1997

Phys. Rev. Lett.

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The pressure induced semiconductor to metal transition in the rare earth compound TmTe has been investigated with electrical resistivity measurements under high pressure. At room temperature, the resistivity showed an exponential decrease up to 2 GPa, indicating a linear closing of the energy gap, followed by an almost pressure independent metallic regime. The resistivity in the metallic regime showed a logarithmic temperature dependence reminiscent of a Kondo effect and a TmSe-like anomaly appeared at low temperature and above 5 GPa. At 5.7 GPa the resistivity showed an abrupt decrease that corresponded to the structural phase transition. [S0031-9007(97)02350-8] PACS numbers: 75.20.Hr, 75.30.MbElectrons move in solids interacting with each other by the Coulomb force. To know the electronic state in a solid is fundamentally a many body problem. Band theory, a mean field theory to treat this problem, has been successful for many kinds of materials, but it is not able to explain the properties of d or f electron systems in which the interactions among the electrons are strong. A wide variety of magnetic and transport properties arise from the correlations among d or f electrons: metal-insulator transition, itinerant magnetism, valence fluctuation, Kondo effect, heavy fermions and superconductivity, and so on. These are now called strongly correlated electron systems and many new concepts on solid state physics have been constructed. However, there are still many problems to be solved and the understanding of these systems is not complete.The Tm monochalcogenide series, which crystallize in the NaCl structure, is one of these mysterious strongly correlated electron systems. TmSe has been studied from the standpoint of the valence fluctuation between 4f 12 and 4f 13 , Kondo effect, antiferromagnetic order, and metal-insulator transition. This compound has the peculiarity that two magnetic valence states Tm 21 and Tm 31 are concerned in the valence fluctuation. However, the situation is so complicated that there is no clear explanation of the physical properties of this compound.TmTe is a divalent semiconductor with thirteen 4f electrons (with one 4f hole). The lattice constant and the Curie constant show that the Tm ions in TmTe are divalent at ambient pressure [1]. The localized 4f 13 level is situated within the energy gap between a filled Te-5p valence band and an empty Tm-5d conduction band [2,3]. The gap D for the electronic excitation of one 4f electron from the localized 4f level to the 5d conduction band is estimated to be 350 meV [4].In TmSe, due to the smaller ion radius of Se than that of Te, the closer distance between Tm ions leads to an increase in the strength of the crystalline field that splits the 5d band into 5d-e g and 5d-t 2g bands [2]. Consequently the energy gap D between the 4f level and the bottom of the conduction band is narrowed. Then the valence fluctuating state appears due to the strong mixing between the 4f electrons and the 5d conduction electrons. In TmSe, both the lattice constant a...

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Valence instabilities of Tm in its compounds and solid solutions

Cited by 39 publications

References 15 publications

Electronic structure and magneto-optical Kerr effect of Tm monochalcogenides

Electronic structure and magneto-optical Kerr effect of Tm monochalcogenides

Electronic Structure of Mixed Valent Systems

Pressure Induced Semiconductor to Metal Transition in TmTe

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