  
|
     
|
The European Physical Journal B
ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)
Abstract Volume 2 Issue 3 (1998) pp 371-380
Effect of electron correlation on superconducting pairing symmetry
M. Mitra (1), H. Ghosh (2) (a), S.N. Behera (1)
(1) Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005, India
(2) Instituto de Física, Universidade Federal Fluminense, Campus da praia Vermelha, Av. Litorânea s/n, 24210-340 Niterói Rio de Janeiro, Brazil
Received: 26 August 1997 / Revised: 31 December 1997 / Accepted: 28 January 1998
Abstract: The role of electron correlation on different pairing symmetries are discussed in details where the electron correlation has been treated within the slave boson formalism. It is shown that for a pure s or pure d wave pairing symmetry, the electronic correlation suppresses the s wave gap magnitude (as well as the $T_{\rm c}$) at a faster rate than that for the d wave gap. On the other hand, a complex order parameter of the form (${\rm s}+i{\rm d}$) shows anomalous temperature dependence. For example, if the temperature ($T_{\rm c}^{\rm d}$) at which the d wave component of the complex order parameter vanishes happens to be larger than that for the s wave component ($T_{\rm c}^{\rm s}$), then the growth of the d wave component is arrested with the onset of the s wave component of the order parameter. In this mixed phase however, we find that the suppression in different components of the gap as well as the corresponding $T_{\rm c}$ due to coulomb correlation are very sensitive to the relative pairing strengths of s and d channels as well as the underlying lattice. Interestingly enough, in such a scenario (for a case of $T_{\rm c}^{\rm s} \gt T_{\rm c}^{\rm d}$)the gap magnitude of the d wave component increases with electron correlation but not $T_{\rm c}^{\rm d}$ for certain values of electron correlation. However, this never happens in case of the s wave component. We also calculate the temperature dependence of the superconducting gap along both the high symmetry directions ( $\Gamma - M$ and $\Gamma - X$) in a mixed ${\rm s}+i{\rm d}$ symmetry pairing state and the thermal variation of the gap anisotropy [0pt][0pt] with electron correlation. The results are discussed with reference to experimental observations.
PACS. 74.25.Dw Superconductivity phase diagrams - 74.62.-c Transition temperature variations - 74.20.Fg BCS theory and its development
(a) email: hng@if.uff.br
Online publication: May 27, 1998
LINK Helpdesk
© EDP Sciences, Springer-Verlag 1998