Temperature-dependent gap edge in strong-coupling superconductors determined using the Eliashberg-Nambu formalism


Autoria(s): Zheng, Xue
Data(s)

10/03/2008

Resumo

Using the theory of Eliashberg and Nambu for strong-coupling superconductors, we have calculated the gap function for a model superconductor and a selection of real superconductors includong the elements Al, Sn, Tl, Nb, In, Pb and Hg and one alloy, Bi2Tl. We have determined thetemperature-dependent gap edge in each and found that in materials with weak electron-phonon ($\lambda 1.20$), not only is the gap edge double valued but it also departs significantly from the BCS form and develops a shoulderlike structure which may, in some cases, denote a gap edge exceeding the $T = 0$ value. These computational results support the insights obtained by Leavens in an analytic consideration of the general problem. Both the shoulder and double value arise from a common origin seated in the form of the gap function in strong coupled materials at finite temperatures. From the calculated gap function, we can determine the densities of states in the materials and the form of the tunneling current-voltage characteristics for junctions with these materials as electroddes. By way of illustration, results are shown for the contrasting cases of Sn ($\lambda=0.74$) and Hg ($\lambad=1.63$). The reported results are distinct in several ways from BCS predictions and provide an incentive determinative experimental studies with techniques such as tunneling and far infrared absorption.

Formato

application/pdf

Identificador

http://pure.qub.ac.uk/portal/en/publications/temperaturedependent-gap-edge-in-strongcoupling-superconductors-determined-using-the-eliashbergnambu-formalism(9924e984-6af8-4cfd-b0f0-41e357830ae3).html

http://dx.doi.org/10.1103/PhyRevB.77.104510

http://pure.qub.ac.uk/ws/files/849732/paper1.pdf

Idioma(s)

eng

Direitos

info:eu-repo/semantics/restrictedAccess

Fonte

Zheng , X 2008 , ' Temperature-dependent gap edge in strong-coupling superconductors determined using the Eliashberg-Nambu formalism ' Physical Review B (Condensed Matter) , vol 77 , no. 10 , 104510 , pp. 104510-1-104510-11 . DOI: 10.1103/PhyRevB.77.104510

Palavras-Chave #/dk/atira/pure/subjectarea/asjc/3100/3104 #Condensed Matter Physics
Tipo

article