Spin Fluctuations in Eliashberg Theory

Abstract

<p>In this thesis, we have studied the properties of a superconductor in which there are two competing dynamical interactions. One of the interactions promotes the pairing, while the other is pair breaking. We have studied the model in the framework of Eliashberg theory for the complete range of coupling strengths. from weak coupling (BCS) to the extreme strong coupling limit. We find that there are distinctive signatures in the specific heat results that are not found in a model with no dynamical pair breaking.</p> <p>The work was motivated by the fact that the parent compounds of most of the high-Tc superconductors are antiferromagnetic insulators. In the superconducting state, spin fluctuations have been observed, at least in LaSrCuO and YBaCuO. For an s-wave superconductor, spin fluctuations are pair breaking. The observed thermodynamic data are consistent with the model that we have studied.</p>