Co-operative Kondo effect in the two-channel Kondo lattice

Abstract

We examine how the properties of a single-channel Kondo lattice model are modified by additional screening channels. Contrary to current wisdom, additional screening channels appear to constitute a relevant perturbation which destabilizes the Fermi liquid. This instability involves two stages. When a heavy Fermi surface develops, it generates zero modes for Kondo singlets to fluctuate between screening channels of different symmetry, producing a divergent composite pair susceptibility. Additional screening channels couple to these divergent fluctuations, promoting an instability into a superconducting state with long-range composite order. We discuss possible implications for heavy fermion superconductivity. ͓S0163-1829͑99͒04629-9͔

Two-channel Kondo lattice model on a ladder studied by the density-matrix renormalization-group method

“…Motivated by experimental 11 and theoretical considerations about the phase diagram of Kondo lattice models, 21 we have used the density matrix renormalization group method 22 to study the strong coupling limit of a Kondo lattice model with two different interactions: the conventional on-site Kondo exchange (J s ) and a d-wave exchange coupling (J d ). Our purpose has been to map the phase diagram of this model and sort out whether or not it displays a phase transition.…”

Mean-field description of odd-frequency superconductivity with staggered ordering vector

“…Theoretically possible realizations of the OF superconductivity in bulk systems are proposed in electron systems such as the t-J model [4], Kondo and Anderson lattices [5][6][7][8][9][10][11][12][13][14][15][16], geometrically frustrated system [17], quantum critical regime [18][19][20], quasi-one-dimensional systems [21][22][23][24], and electron-phonon coupled systems [25,26]. However, using mean-field-type theory, it has been shown that the second-order phase transition into the OF superconductivity is unstable in general [27,28].…”

Nodal to Nodeless Superconducting Energy-Gap Structure Change Concomitant with Fermi-Surface Reconstruction in the Heavy-Fermion CompoundCeCoIn5

“…Here, superconductivity arises from cooperative Kondo screening, where two electrons screen the same local moment to form a composite pair [56]. This process is local and does not require an underlying scale.…”