Crystal structure and magnetic properties of CeTe2

Stöwe, Klaus

doi:10.1016/s0925-8388(00)00799-4

Cited by 41 publications

(46 citation statements)

References 21 publications

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“…This finding indicates that the CDW states in the Te͑1͒ sheets of CeTe 2 are not consistent with the 2 ϫ 1 lattice deformation, and that it is very likely that they arise from the 2 ϫ 2 deformation. 7 It is implied here that the domain size of the 2 ϫ 2 CDW states is larger than the beam spot ͑ϳ50 m͒. This finding is in agreement with the recent finding of RTe 2 , 14 but makes a contrast to the case of RTe 3 ͑R =Ce,Sm͒, which has two adjacent Te͑1͒ sheets instead of one in the unit cell, and shows an ARPES gap feature of an apparently twofold symmetry.…”

supporting

confidence: 91%

Charge-density wave gap and Ce4fstates inCeTe2observed by photoemission spectroscopy

et al. 2006

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The electronic structure of an f-electron charge-density-wave ͑CDW͒ system, CeTe 2 , has been investigated using high-resolution angle-resolved photoemission spectroscopy ͑ARPES͒. Two gaps of ϳ100 and ϳ500 meV have been observed both along ⌫X and ⌫Y, implying the 2 ϫ 2 lattice deformation in the Te͑1͒ sheets with the CDW gap of Ϸ100 meV. By employing the fine-structure ͑FS͒ resonance, the experimental Ce 4f ARPES spectra have been measured. The FS resonance ARPES shows a typical two-peak structure with the peaks at ϳ−4 and ϳ−1 eV, and the weight shift in the latter peak in contrast to the traditional giant resonance. The Ce 4f states have the negligibly small intensity near E F , reflecting the minor contribution from Ce 4f electrons to the metallic ground state of CeTe 2 . This study reveals that the carriers near E F should have mainly the Te͑1͒ 5p and Ce 5d character, but that only the Ce 5d bands cross E F . Recent observation of the pressure-induced superconductivity ͑T C = 2.7 K͒ in nonstoichiometric CeTe 2 , which is a charge-density-wave ͑CDW͒ f-electron system ͑T CDW ϳ 1000 K͒, has raised the fundamental question on the interplay between superconductivity, magnetism, and the CDW state. 1 CeTe 2 shows the strong anisotropic behavior in transport and magnetic properties, 2-4 which arise from the quasitwo-dimensional layered structure. CeTe 2 crystallizes in the layered Cu 2 Sb-type tetragonal structure with two types of Te sites: Te͑1͒ and Te͑2͒. Te͑1͒ atoms form planar square sheets, which are sandwiched along the c axis ͓001͔ by the corrugated double layers of Ce and Te͑2͒ atoms ͓Fig. 1͑a͔͒. The ionic configuration of CeTe 2 is considered to be Ce 3+ Te͑2͒ 2− Te͑1͒ 1− so as to produce hole carriers in the Te͑1͒ sheets. The square net of Te͑1͒, which consists of the mutually orthogonal linear chains that are partially filled, would be easily distorted by the Peierls-like mechanism. 5 Indeed, CeTe 2 shows the pseudogap feature 6 and the superstructure, 7 which are believed to be related with the CDW instability. According to break junction tunneling ͑BJT͒ measurements, CeTe 2 showed a V-shaped density of states ͑DOS͒ with 2⌬ BJT = 1.2 eV and another smaller gap of 2⌬ Ã = 0.5 eV. 6 Band-structure calculations indicate that the CDW instability occurs due to the nesting between the electron and hole Fermi surfaces in the Te͑1͒ square sheets along the ͓100͔ direction in the ab plane. 6,[9][10][11][12] The superconducting phase in CeTe 1.82 seems to coexist with the CDW and magnetic phases. This is reminiscent of superconducting transition-metal dichalchogenides. For example, layered 2H-NbSe 2 exhibits the incommensurate CDW transition below 35 K and the phonon-mediated superconductivity at T c = 7.2K, 8 for which the superconducting carriers are known to be Nb 4d electrons. In contrast, the carrier type in CeTe 2−␦ has not been clarified experimentally yet, which is crucial in understanding the origin of superconductivity. Therefore there are still open issues in the electronic structure of CeTe 2−␦ , such as ...

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confidence: 91%

Charge-density wave gap and Ce4fstates inCeTe2observed by photoemission spectroscopy

et al. 2006

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“…The anisotropic temperature factor exponent takes the form: (6) Te14-1Tb8 0.3898 (6) reported in Refs. [2][3][4][5]. Since the Te13 and Te14 sites are only occupied by 50%, no more than one of two adjacent positions will be occupied.…”

Section: Resultsmentioning

confidence: 99%

“…The crystal structures of the compounds LaTe 2 (space group Pc, a = 0.9190 nm, b = 0.9107 nm, c = 0.9070 nm, β = 90.04 • ) [2], CeTe 2 (space group P4, a = 0.89975 nm, c = 1.8212 nm) [3], PrTe 2 (space group P4, a = 0.89680 nm, c = 1.8119 nm) [4], SmTe 2−x (space group P4 2 /n, a = 0.9709 nm, c = 1.8007 nm) [5] and GdTe 2−x (space group P4/n, a = 0.9640 nm, c = 1.7924 nm) [6] have been completely investigated.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of the TbTe1.8 compound

Gulay¹,

Stȩpień‐Damm²,

Daszkiewicz³

et al. 2007

Journal of Alloys and Compounds

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“…of CeTe 2 ͒ with the P4 space group͔ which has the double herringbone patterns. 10 As shown in Fig. 3, the opening of the CDW gap for the CDW-distorted CeTe 2 ͑denoted by the dotted line͒ is evident, i.e., the DOS near E F is suppressed much as compared to that of the nondistorted CeTe 2 ͑solid line͒.…”

Section: Resultsmentioning

confidence: 78%

“…On the other hand, the isostructural LaTe 2 is reported to have the charge density wave ͑CDW͒ instability along ͓100͔ direction that arises from the nesting between the electron and hole Fermi surfaces in the Te͑1͒ square sheet. 7,8 CeTe 2 also reveals the pseudo-gap feature 9 and the superstructure, 10 which are believed to be related to the CDW. Interestingly, the superconducting phase in CeTe 1.82 seems to coexist with the CDW and magnetic phases.…”

Section: Introductionmentioning

confidence: 94%

Electronic and magnetic structures of CeTe2

Shim

Youn

Park

et al. 2005

Journal of Applied Physics

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We have investigated electronic structures of CeTe2 to explore the correlation between the magnetic, charge density wave, and superconducting phases by using the local spin density approximation (LSDA) and LSDA+U (U=on-site Coulomb interaction) methods. We have found that the contribution near EF from Ce 4f states is negligible, suggesting that Ce 4f electrons are not the superconducting carriers. The total energy calculation indicates that the ABBA-type antiferromagnetic configuration is the most stable, while the stability is weakened by pressure. We have discussed the possible superconducting mechanism in the magnetic phase of CeTe1.82.

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Crystal structure and magnetic properties of CeTe2

Cited by 41 publications

References 21 publications

Charge-density wave gap and Ce4fstates inCeTe2observed by photoemission spectroscopy

Charge-density wave gap and Ce4fstates inCeTe2observed by photoemission spectroscopy

Crystal structure of the TbTe1.8 compound

Electronic and magnetic structures of CeTe2

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