Ground State and Thermodynamic Properties of an Induced-Pairing Model

• Authors: G. Pawłowski , S. Robaszkiewicz
• Languages of publication: EN

Abstracts

EN

We study the phase diagrams and thermodynamic properties of a system of coexisting wide-band current carriers (c-particles) and narrow-band electrons (d-electrons) which can form local pairs. There are two distinct mechanisms of superconductivity in the model considered: (i) the intersubsystem charge exchange, which leads to the superconducting state involving both types of electrons and (ii) the pair hopping interaction of d-electrons, leading to the superconducting state of d-particles only. In contrast to previous works on the subject, we assume an arbitrary value of on-site density interaction of d-electrons U, which allows us to study the effects of reduced d-pair binding energy. Within the approach in which the U term is exactly treated we determine the evolution of superconducting properties as a function of interactions and relative position of the bands. In a definite range of parameters the system shows features which are intermediate between those of a local pair superconductor and those of a classical BCS model. The increasing on-site Coulomb repulsion U competing with the intersubsystem charge exchange and the pair hopping interaction reduces the superconducting critical temperature. Moreover, it can induce a change of the superconducting transition into the first order one. Above a critical value of U, dependent on concentration of electrons and other interactions, the superconducting state cannot be stable at any temperature.

Keywords

EN

74.20.-z; 71.28.+d; 74.25.Ha

Discipline

• 74.25.Ha: Magnetic properties including vortex structures and related phenomena(for vortices, magnetic bubbles, and magnetic domain structure, see 75.70.Kw)
• 74.20.-z: Theories and models of superconducting state
• 71.28.+d: Narrow-band systems; intermediate-valence solids(for magnetic aspects, see 75.20.Hr and 75.30.Mb in magnetic properties and materials)

• Journal: Acta Physica Polonica A
• Year: 1998
• Volume: 94
• Issue: 4
• Pages: 683-699

Dates

published

1998-10

received

1998-07-09

Contributors

author

G. Pawłowski

• Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

author

S. Robaszkiewicz

• Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

Identifiers

DOI

10.12693/APhysPolA.94.683