Article

Extremely strong coupling superconductivity in artificial two-dimensional Kondo lattices

Nature Physics (Impact Factor: 19.35). 09/2011; 7(11). DOI: 10.1038/nphys2112
Source: arXiv

ABSTRACT When interacting electrons are confined to low-dimensions, the
electron-electron correlation effect is enhanced dramatically, which often
drives the system into exhibiting behaviors that are otherwise highly
improbable. Superconductivity with the strongest electron correlations is
achieved in heavy-fermion compounds, which contain a dense lattice of localized
magnetic moments interacting with a sea of conduction electrons to form a 3D
Kondo lattice. It had remained an unanswered question whether superconductivity
would persist upon effectively reducing the dimensionality of these materials
from three to two. Here we report on the observation of superconductivity in
such an ultimately strongly-correlated system of heavy electrons confined
within a 2D square-lattice of Ce-atoms (2D Kondo lattice), which was realized
by fabricating epitaxial superlattices built of alternating layers of
heavy-fermion CeCoIn5 and conventional metal YbCoIn5. The field-temperature
phase diagram of the superlattices exhibits highly unusual behaviors, including
a striking enhancement of the upper critical field relative to the transition
temperature. This implies that the force holding together the superconducting
electron-pairs takes on an extremely strong coupled nature as a result of
two-dimensionalization.

0 Bookmarks
 · 
67 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: dc magnetization measurements on CeCoIn5 reveal a first-order phase transition at Hc2 for both H‖a and c axes in the isothermal magnetization M(H) below 0.7 K, indicating a strong Pauli paramagnetic suppression in the even-parity pairing. M(T) in the normal state above Hc2 exhibits non-Fermi-liquid behavior down to 150 mK, implying the existence of antiferromagnetic fluctuations behind the unconventional superconductivity. We observed an unusual peak effect for H‖c in fields 5–30 kOe below 150 mK(=0.06Tc), whose anomalous temperature dependence cannot be simply explained by ordinary mechanisms.
    Phys. Rev. B. 01/2002; 65(18).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Intermetallic compounds containing f-electron elements display a wealth of superconducting phases, that are prime candidates for unconventional pairing with complex order parameter symmetries. For instance, superconductivity has been found at the border of magnetic order as well as deep within ferro- and antiferromagnetically ordered states, suggesting that magnetism may promote rather than destroy superconductivity. Superconductivity near valence transitions, or in the vicinity of magneto-polar order are candidates for new superconductive pairing interactions such as fluctuations of the conduction electron density or the crystal electric field, respectively. The experimental status of the study of the superconducting phases of f-electron compounds is reviewed. Comment: Rev. Mod. Phys. in print; 75 pages, 23 figures; comments welcome
    Review of Modern Physics 05/2009; · 44.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An analysis of the resistivity above Tc in the oxide superconductors shows that the inelastic-scattering rate is several times kT. This inelastic scattering yields pair breaking which suppresses Tc relative to the energy gap. The large energy scale in the problem suggests an electronic pairing mechanism, which we believe leads to d-wave pairing. The inelastic scattering has contributions from electron-phonon and from electron-electron scattering in a two-dimensional square lattice near half filling. In the latter case, the pair breaking can be reduced in a more three-dimensional structure.
    Physical Review Letters 07/1987; 58(25):2691-2694. · 7.73 Impact Factor

Full-text (2 Sources)

View
19 Downloads
Available from
May 23, 2014