منابع مشابه
Mixed Valence Model for Superconductivity
Superconductivity often occurs in crystals with one active electron per site with charge density wave (CDW) or spin density wave (SDW) as ’mother state’. It is proposed that superconductivity is possible when the differences in equilibrium geometry and energy between the diabatic CDW and SDW states are so small that there is interaction between them via the zero point vibrations. Electron pairi...
متن کاملMixed valence and superconductivity.
Mixed-valence (MV) systems are referred to here as MV-2 and MV-3 depending on whether two or three consecutive valence states are involved. MV-3 systems range from systems with Hubbard U>>0, corresponding to a single stable, intermediate valence state, and U<<0, corresponding to stable alternating valences differing by two units. Experiments using inelastic neutron scattering or inelastic X-ray...
متن کاملValence fluctuationmediated superconductivity inCeCu2Si2
It has been proposed that there are two types of superconductivity in CeCu2Si2, mediated by spin fluctuations at ambient pressure, and by critical valence fluctuations around a charge instability at a pressure Pv ≃ 4.5 GPa. We present in detail some of the unusual features of this novel type of superconducting state, including the coexistence of superconductivity and huge residual resistivity o...
متن کاملMixed valence europium nitridosilicate Eu2SiN3.
The mixed valence europium nitridosilicate Eu(2)SiN(3) has been synthesized at 900 degrees C in welded tantalum ampules starting from europium and silicon diimide Si(NH)(2) in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a = 542.3(11) pm, b = 1061.0(2) pm, c = 1162.9(2) pm, Z = 8, 767 independent reflections...
متن کاملMixed valence/dipole-bound dianions
The possibility of binding two electrons to a molecule utilizing two distinct electron binding sites ~i.e., one valenceand one dipole-binding center! is studied using ab initio electronic structure methods. It is found that if the electron binding energy of the dipole-binding site is large enough to overcome the Coulomb repulsion produced by the valence-bound electron, the dianion can be electr...
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ژورنال
عنوان ژورنال: Brazilian Journal of Physics
سال: 2003
ISSN: 0103-9733
DOI: 10.1590/s0103-97332003000400022