Related papers: Sub-ohmic two-level system representation of the K…
We study a strongly interacting quantum dot connected to two superconducting leads using a slave-spin representation of the dot. At the mean-field level, the problem maps to a resonant level model with superconducting leads, coupled to an…
The single impurity Kondo model at zero temperature in a magnetic field is solved by a semi-analytical approach based on the flow equation method. The resulting problem is shown to be equivalent to a resonant level model with a non-constant…
In a recent paper of Nandkishore and Senthil [arxiv:1201.5998 (2012)], a concept of orthogonal metal has been introduced to reinterpret the disordered state of slave-spin representation in the Hubbard model as an exotic gapped metallic…
We derive a solvable resonant-level type model, to describe an impurity spin coupled to zero-energy bound states localized at the edge of a one dimensional d-wave superconductor. This results in a two-channel Kondo effect with a quite…
We review a recently developed method, based on a pseudoparticle representation of correlated electrons, to describe both Fermi liquid and non-Fermi liquid behavior in quantum impurity systems. The role of the projection onto the physical…
Many-body correlations and macroscopic quantum behaviors are fascinating condensed matter problems. A powerful test-bed for the many-body concepts and methods is the Kondo model which entails the coupling of a quantum impurity to a…
The renormalization group formalism was applied to calculate the spin-lattice relaxation rate of a well-defined magnetic moment in the neighborhood of a spin degenerate Anderson impurity. In the Kondo regime, the spin-lattice relaxation…
The Kondo effect may develop in those cases where there are non-commuting operators describing the interaction between the conduction electrons and impurities or defects with internal degrees of freedom. This interaction may involve spin or…
Wilson's Numerical Renormalization Group method is used to study the paramagnetic ground state of the periodic Anderson model within the dynamical mean-field approach. For the particle-hole symmetric model, which is a Kondo insulator, we…
In the two-impurity Anderson model, the inter-impurity spin exchange interaction favors a spin singlet state between two impurities leading to the breakdown of the Kondo effect. We show that a local uniform magnetic field can delocalize the…
An approximate partition functional is derived for the infinite-dimensional Hubbard model. This functional naturally includes the exact solution of the Falicov-Kimball model as a special case, and is exact in the uncorrelated and atomic…
Spin-flip scattering from magnetic impurities has a strong pair-breaking effect in $s$-wave superconductors where increasing the concentration of impurities rapidly destroys superconductivity. For small Kondo temperature $T_K$ the…
A multichannel Kondo model, where two or more equivalent but independent channels of electrons compete to screen a spin-1/2 impurity, shows overcompensation of the impurity spin, leading to the non-Fermi-liquid behavior in various…
The thermodynamics of a lattice regularized asymmetric Anderson impurity in a correlated host is obtained by an exact solution. The crossover from the Anderson- to the Kondo-regime is studied, thus making contact with predictions by scaling…
Thermodynamic properties of the one-dimensional Kondo lattice model at half-filling are studied by the density matrix renormalization group method applied to the quantum transfer matrix. Spin susceptibility, charge susceptibility, and…
A mean field spherical model with random couplings between pairs, quartets, and possibly higher multiplets of spins is considered. It has the same critical behavior as the Sherrington-Kirkpatrick model. It thus exhibits replica symmetry…
I consider models with an impurity spin coupled to a fluctuating gaussian field with or without additional Kondo coupling of the conventional sort. In the case of isotropic fluctuations, the renormalisation group flows for these models have…
We study the occurrence of symmetry breakings, at zero and finite temperatures, in the J_1-J_3 antiferromagnetic Heisenberg model on the square lattice using Schwinger boson mean field theory. For spin-1/2 the ground state breaks always the…
We investigate Kondo correlations in a quantum dot with normal and superconducting electrodes, where a spin bias voltage is applied across the device and the local interaction $U$ is either attractive or repulsive. When the spin current is…
Using analytical arguments and the numerical renormalization group method we investigate the spin-thermopower of a quantum dot in a magnetic field. In the particle-hole symmetric situation the temperature difference applied across the dot…