ODD-FREQUENCY PAIRING IN THE KONDO-LATTICE

Citation
P. Coleman et al., ODD-FREQUENCY PAIRING IN THE KONDO-LATTICE, Physical review. B, Condensed matter, 49(13), 1994, pp. 8955-8982
Citations number
70
Categorie Soggetti
Physics, Condensed Matter
ISSN journal
01631829
Volume
49
Issue
13
Year of publication
1994
Pages
8955 - 8982
Database
ISI
SICI code
0163-1829(1994)49:13<8955:OPITK>2.0.ZU;2-J
Abstract
We discuss the possibility that heavy-fermion superconductors involve odd-frequency triplet pairing. A key technical innovation here is a Ma jorana representation for the local moments which avoids the use of a Gutzwiller projection. We employ the Kondo lattice model and develop a mean-field theory for odd-frequency pairing that entails pairing betw een local moments and conduction electrons, as described by a spinor o rder parameter. We confirm that the Meissner stiffness is positive and the state is stable. A residual band of gapless quasiparticles whose spin and charge coherence factors vanish linearly in energy, decouples from the condensate. The unusual energy dependence of these coherence factors leads to a T3 NMR relaxation rate at a conduction electron si te that coexists with a linear specific heat. Two verifiable predictio ns of the theory are (i) that a Korringa relaxation will fail to devel op in heavy-fermion superconductors, even in the limit of strong pair breaking and severe gaplessness and (ii) that the hither-to unmeasured NMR relaxation rate at the actinide or rare-earth site will become ex ponentially activated in the superconducting phase.