1,995,996 research outputs found
Electronic Structure of ZnCNi3
According to a recent report by Park et al, ZnCNi3 is isostructural and
isovalent to the superconducting (Tc = 8 K) anti-perovskite, MgCNi3, but shows
no indication of a superconducting transition down to 2K. A comparison of
calculated electronic structures shows that the main features of MgCNi3,
particularly the van Hove singularity near the Fermi energy, are preserved in
ZnCNi3. Thus the reported lack of superconductivity in ZnCNi3 is not
explainable in terms of Tc being driven to a very low value by a small Fermi
level density of states. We propose that the lack of superconductivity, the
small value of the linear specific heat coefficient, gamma, and the discrepancy
between theoretical and experimental lattice constants can all be explained if
the material is assumed to be a C-deficient alpha-ZnCNi3 similar to the
analogous non-superconducting phase of MgCNi3
ELECTRONIC STRUCTURE OF FeSi
The full set of high-energy spectroscopy measurements including X-ray
photoelectron valence band spectra and soft X-ray emission valence band spectra
of both components of FeSi (Fe K_beta_5, Fe L_alpha, Si K_beta_1,3 and Si
L_2,3) are performed and compared with the results of ab-initio band structure
calculations using the linearized muffin-tin orbital method and linearized
augmented plane wave method.Comment: 11 pages + 3 PostScript figures, RevTex3.0, to be published in
J.Phys.:Cond.Matte
Electronic Structure of Sr_2FeMoO_6
We have analysed the unusual electronic structure of Sr_2FeMoO_6 combining
ab-initio and model Hamiltonian approaches. Our results indicate that there are
strong enhancements of the intraatomic exchange strength at the Mo site as well
as the antiferromagnetic coupling strength between Fe and Mo sites. We discuss
the possibility of a negative effective Coulomb correlation strength (U_{eff})
at the Mo site due to these renormalised interaction strengths.Comment: To appear in Phys. Rev. Let
Electronic structure of underdoped cuprates
We consider a two-dimensional Fermi liquid coupled to low-energy commensurate
spin fluctuations. At small coupling, the hole Fermi surface is large and
centered around . We show that as the coupling increases, the
shape of the quasiparticle Fermi surface and the spin-fermion vertex undergo a
substantial evolution. At strong couplings, , where
is the upper cutoff in the spin susceptibility, the hole Fermi surface consists
of small pockets centered at . Simultaneously, the full
spin-fermion vertex is much smaller than the bare one, and scales nearly
linearly with , where is the momentum of the susceptibility. At
intermediate couplings, there exist both, a large hole Fermi surface centered
at , and four hole pockets, but the quasiparticle residue is small
everywhere except for the pieces of the pockets which face the origin of the
Brillouin zone. The relevance of these results for recent photoemission
experiments in and systems is discussed.Comment: 19 pages, RevTeX, 15 figures embedded in the text, submitted to Phys.
Rep., ps-file is also available at
http://lifshitz.physics.wisc.edu/www/morr/morr_homepage.htm
Surface electronic structure of Sr2RuO4
We have addressed the possibility of surface ferromagnetism in Sr2RuO4 by
investigating its surface electronic states by angle-resolved photoemission
spectroscopy (ARPES). By cleaving samples under different conditions and using
various photon energies, we have isolated the surface from the bulk states. A
comparison with band structure calculations indicates that the ARPES data are
most readily explained by a nonmagnetic surface reconstruction.Comment: 4 pages, 4 figures, RevTex, submitted to Phys. Rev.
Electronic structure of Fe1.04(Te0.66Se0.34)
We report the electronic structure of the iron-chalcogenide superconductor,
Fe1.04(Te0.66Se0.34), obtained with high resolution angle-resolved
photoemission spectroscopy and density functional calculations. In
photoemission measurements, various photon energies and polarizations are
exploited to study the Fermi surface topology and symmetry properties of the
bands. The measured band structure and their symmetry characters qualitatively
agree with our density function theory calculations of Fe(Te0.66Se0.34),
although the band structure is renormalized by about a factor of three. We find
that the electronic structures of this iron-chalcogenides and the
iron-pnictides have many aspects in common, however, significant differences
exist near the Gamma-point. For Fe1.04(Te0.66Se0.34), there are clearly
separated three bands with distinct even or odd symmetry that cross the Fermi
energy (EF) near the zone center, which contribute to three hole-like Fermi
surfaces. Especially, both experiments and calculations show a hole-like
elliptical Fermi surface at the zone center. Moreover, no sign of spin density
wave was observed in the electronic structure and susceptibility measurements
of this compound.Comment: 7 pages, 9 figures. submitted to PRB on November 15, 2009, and
accepted on January 6, 201
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