https://doi.org/10.1140/epjb/e20020127
Dual model for magnetic excitations and superconductivity in UPd2Al3
Max-Planck-Institute for Chemical Physics of Solids,
01187 Dresden, Germany
Corresponding author: a thalm@cpfs.mpg.de
Received:
22
October
2001
Revised:
28
February
2002
Published online: 15 May 2002
The Heavy Fermion state in UPd2Al3 may be approximately described by
a dual model where two of the three U-5f electrons are in a localized
state split by the crystalline electric field into two low lying
singlets with a splitting energy meV. The third 5f electron
has itinerant character and forms the Heavy Electron
bands. Inelastic neutron scattering and tunneling experiments suggest
that magnetic excitons, the collective propagating crystal field
excitations of the localized 5f electrons, mediate superconducting (sc)
pairing in UPd2Al3. A theory for this novel mechanism is developed within a
nonretarded approach. A model for the magnetic
exciton bands is analyzed and compared with experiment. The sc pair
potential which they mediate is derived and the gap
equations are solved. It is shown that this mechanism
favors an odd parity state which is nondegenerate due to the
combined symmetry breaking by the crystalline electric field and the AF
order parameter. A hybrid model including the spin fluctuation contribution
to the pairing is also discussed.
PACS: 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.) / 74.20.Rp – Pairing symmetries (other than s-wave)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002