10,529 research outputs found
Topological Confinement and Superconductivity
We derive a Kondo Lattice model with a correlated conduction band from a
two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence
of a robust pairing mechanism in a model that only contains repulsive
interactions. The mechanism is due to topological confinement and results from
the interplay between antiferromagnetism and delocalization. By using
Density-Matrix-Renormalization-Group (DMRG), we demonstrate that this mechanism
leads to dominant superconducting correlations in a 1D-system.Comment: 4 pages, 4 figure
Evidence of quantum criticality in the doped Haldane system Y2BaNiO5
Experimental bulk susceptibility X(T) and magnetization M(H,T) of the
S=1-Haldane chain system doped with nonmagnetic impurities, Y2BaNi1-xZnxO5
(x=0.04,0.06,0.08), are analyzed. A numerical calculation for the low-energy
spectrum of non-interacting open segments describes very well experimental data
above 4 K. Below 4 K, we observe power-law behaviors, X(T)=T^-alpha and
M(H,T)/T^(1-alpha)=f(alpha,(H/T)), with alpha (<1) depending on the doping
concentration x.This observation suggests the appearance of a gapless quantum
phase due to a broad distribution of effective couplings between the
dilution-induced moments.Comment: 4 pages, 3 figure
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