Vibronic origins of highTc

Hardy, J. R.; Flocken, J. W.

doi:10.1080/01411599008207219

Cited by 8 publications

References 51 publications

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On the composition‐dependent isotope effect of HTSC in the two‐band model

1993

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The oxygen isotope effect in high-T, superconductors has been investigated on the basis of a two-band model where superconducting phase transition is induced by interband (mainly Coulombic) interaction. The isotope shift of Tc appears due to the dependence of averaged interband electronphonon coupling constant on oxygen mass. This coupling has a repulsive nature and gives a relatively small contribution to the total interaction inducing superconductivity. The calculated isotope effect exponent depending on the carrier concentration has been compared with the experimental one as a function of x for La2-,Sr,Cu0,.

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On the composition‐dependent isotope effect of HTSC in the two‐band model

1993

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On the Possibility of High‐T_c's in Connection with the Dynamical Instability of CuO₂‐Plane‐Oxygens with Captured Holes

Kristoffel

1992

Physica Status Solidi (b)

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There are a lot of approaches trying to explain the microscopic mechanism of highTc superconductivity (HTSC) . However, the problem has still remained unsolved.In this communication we point to another possibility: high-Tc's can be connected with the interaction of dipole moments generated by the out-of-plane distortion of oxygens which have captured injected holes. 2-replacing 0 ) and can generate a number of localized states /1 to 3 1 . In such a way the holes destroy the corresponding band edge and possibly something like an "impurity band" is formed and the hole effective mass becomes enhanced. 2The extra holes can significantly perturb also the lattice dynamics. It is well known that various structural instabilities are present or exist potentially in the new oxide superconductors. For instance, in the Cu-0 chains of YBa Cu 0 2 3 6+6 the O(1)-and 0(4)-type oxygens probably move in some kinds of two-minimum potentials and a number of high-Tc theories exploit the corresponding anharmonic motion of these oxygens / 4 to 9 / .According to / l o / also another dynamical instability of oxygens in the superconductivity-playground CuO planes may be present, which is caused by the extra holes converting 02-. into 0 . This means a strong dynamical perturbation connected with the large difference in the effective radii /11/ of 0-(0.066 nm) and of 02-( 0 . 1 3 6 nm). The author of /11/ uses the idea of the vanishing electron 2 -') Rjia 142, EE-2400, Tartu, Estonia.

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