It is shown that the large-N approach yields two energy scales for Kondo lattice model. The single-impurity temperature, $T_K$, signals onset of local singlet formation, while Fermi liquid coherence sets in only below a lower scale, $T^{\star}$. At low conduction electron density $n_c$ ("exhaustion" limit), ratio $T^{\star}/T_K$ much smaller than unity, and to depend on not coupling. physical meaning these demonstrated by computing several quantities as function temperature.

We study the competition between Kondo effect and frustrating exchange interactions in a Kondo-lattice model within large-${\cal N}$ dynamical mean-field theory. find T=0 phase transition heavy Fermi-liquid spin-liquid for critical value of $J_c = T_{K}^0$, single-impurity temperature. Close to point, Fermi liquid coherence scale $T^\star$ is strongly reduced effective mass enhanced. The regime $T>T^\star$ characterized by magnetic correlations non-Fermi-liquid properties. It suggested that...

We argue that near a Kondo breakdown critical point, spin liquid with spatial modulations can form. Unlike its uniform counterpart, we find this occurs via second order phase transition. The amount of entropy quenched when ordering is the same magnitude as for an antiferromagnet. Moreover, two states are competitive, and at low temperatures separated by first modulated breaks ${Z}_{4}$ symmetry, recently seen in hidden ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$. Based on this, suggest viable...

We use the composite operator method (COM) to analyze strongly correlated repulsive Hubbard model, investigating effect of nearest-neighbor hoppings up fourth order on a square lattice. consider two sets self-consistent equations, one enforcing Pauli principle and other imposing charge-charge, spin-spin, pair-pair correlations using decoupling scheme developed by Roth (1969

Layered Nickelates have gained intensive attention as potential high-temperature superconductors, showing similarities and subtle differences to well-known Cuprates. This study introduces a modelling framework analyze the tunability of electronic structures by focusing on effective orbitals additional Fermi pockets, mimicking doping or external pressure qualitatively. It investigates role $3d_{z^2}$ orbital in interlayer hybridization, which leads formation second pocket surface. The...

In certain Mott-insulating dimerized antiferromagnets, triplet excitations of the paramagnetic phase display both three-particle and four-particle interactions. When such a magnet undergoes quantum transition into magnetically ordered state, interaction becomes part critical theory provided that lattice ordering wave vector is zero. One microscopic example staggered-dimer antiferromagnet on square lattice, for which deviations from O(3) universality have been reported in numerical studies....

The interplay between the Kondo effect and disorder is studied. This done by applying a matrix coherent potential approximation (CPA) treating interaction on mean-field level. resulting equations are shown to agree with those derived dynamical method (DMFT). By formalism Bethe tree structure infinite coordination of diagonal off-diagonal Special attention paid behavior Kondo- Fermi liquid temperature as function concentration ions. non monotonous dependence these quantities discussed.

The thermodynamic and transport properties of intermetallic compounds with Ce, Eu, Yb ions are discussed using the periodic Anderson model an infinite correlation between $f$ electrons. At high temperatures, these systems exhibit typical features that can be understood in terms a single-impurity or Kondo scale ${T}_{K}$. low one often finds normal state governed by Fermi liquid (FL) laws characteristic energy ${T}_{0}$. slave boson solution shows ${T}_{0}$ ${T}_{K}$ depend not only on...

In a superconducting ferromagnet, the state appears in ferromagnetic phase where usually domain structure has already developed. We study influence of screening currents on stripe with out-of-plane magnetization, film arbitrary thickness. find that superconductivity always induces shrinkage domains, and there is critical value penetration depth below which mono-domain more stable than periodic one. Furthermore we investigate possible different effects singlet triplet width, as well...

We have developed a 3D version for the Modulated Spin Liquid in body-centered tetragonal lattice structure to describe hidden order observed URu$_2$Si$_2$ at $T_0\approx17.5$ K. This second transition is well described by our model confirming earlier hypothesis. The symmetry of modulation minimized ${\bf Q}\equiv(1,1,1)$. assume linear variation interaction parameters with spacing and results show good agreement uniaxial pressure experiments.

We consider a magnetic impurity deposited on the surface of strong topological insulator and interacting with modes by Kondo exchange interaction. Taking into account warping Fermi line modes, we derive mapping to an effective one dimensional model show that is fully screened electrons except when level lies exactly at Dirac point. Using Abrikosov fermion mean-field theory, calculate shape electronic density Friedel oscillation resulting from presence screening cloud. analyze quantitatively...

We study the low energy states of Kondo alloys as function magnetic impurity concentration per site, x, and conduction electron average site occupation, nc. Using two complementary approaches, mean-field coherent potential approximation strong coupling limit, we identify characterize different Fermi liquid regimes. propose that both regimes are separated by a Lifshitz transition at x = Indeed, predict discontinuity number quasiparticles which enclosed in surface. This feature could provide...

We analytically study a Kondo lattice model with an additional nearest-neighbor antiferromagnetic interaction in the framework of large-$\mathcal{N}$ theory. find that there is local quantum critical point between two phases, normal Fermi liquid and spin which spins are decoupled from conduction electrons. The susceptibility displays power-law divergence throughout phase. check reliability results by solving Monte Carlo simulation, $\mathcal{N}=2$ spin-liquid problem no electrons, we...

Within the framework of Kondo-Heisenberg model, we analyse effect charge fluctuation on modulated spin liquid (MSL) and antiferromagnetic (AF) orders which were established in a previous publication. We discuss emergence two quantum critical lines separating coexisting Kondo-MSL Kondo-MSL-AF phases. The various order parameters system possess characteristic signature observable electronic band structure each calculate that MSL is indeed possible explanation hidden phase $URu_{2}Si_{2}$ heavy...

Intercarrier correlations in hole doped cuprates are investigated by ab initio multiconfiguration calculations. The dressed carriers display features that reminiscent of both Zhang-Rice (ZR) $\mathrm{Cu}{\mathrm{O}}_{4}$ states and Jahn-Teller polarons. interaction between these quasiparticles is repulsive. At dopings high enough, the interplay long-range unscreened Coulomb interactions phase coherence among O-ion half-breathing vibrations on ZR plaquettes may lead to a strong reduction...

We study the mesoscopic Kondo box, consisting of a quantum spin 1/2 interacting with chaotic electronic bath as can be realized by magnetic impurity coupled to electrons on dot, using mean-field approach for interaction. Its numerical efficiency allows us analyze temperature, local susceptibility, and conductance statistics large number samples energy levels obtained random matrix theory. see pronounced parity effects in average values probability distributions, depending an even odd...

Both the weakly coupled and strong coupling Anderson impurity problems are characterized by a Fermi-liquid theory with interacting quasiparticles. In an box, mesoscopic fluctuations of effective single particle properties will be large. We study how statistical at low temperature in these two connected, using random matrix slave boson mean field approximation (SBMFA). First, for resonant level model such as results from SBMFA, we find joint distribution energy levels without present. Second,...

A polarized electronic Raman scattering study reveals the emergence of symmetry dependence in response single-crystalline ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ below Kondo crossover scale ${T}_{K}\ensuremath{\sim}$ 100 K. In particular, development a coherent pseudogap predominantly ${E}_{g}$ channel highlights strong anisotropy physics that was previously neglected theoretical models this system and more generally has been sparsely treated for systems. calculation vertices demonstrates...

An $SU({\rm n})$-symmetric generalization of the Heisenberg model for quantum spin $S$ operators is used to investigate geometrically frustrated body-centered tetragonal (BCT) lattice with antiferromagnetic interlayer coupling $J_1$ and intralayer first second neighbor $J_2$ $J_3$. Using complementary representations operators, we study phase diagram characterizing ground state system. For small n, find that most stable solutions correspond four different families possible long range...

We study mesoscopic fluctuations in a system which there is continuous connection between two distinct Fermi liquids, asking whether the variation limits correlated. The particular studied an Anderson impurity coupled to finite reservoir described by random matrix theory, structure can be realized using quantum dots. use slave boson mean-field approach connect levels of uncoupled those strong-coupling Nozières' liquid. find strong but not complete correlation properties and several universal...

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français étrangers, laboratoires publics privés.

In this paper, we consider an unconventional doping effect of strongly correlated cerium $4f$ electrons in layered intermetallic systems. The conduction electron part the model is taken to reproduce hole and pockets iron-based superconductors (FeSCs), contribution studied through effective tight-binding Hamiltonian arising from slave-boson mean-field theory periodic Anderson model. We show how consideration nonlocal Kondo coupling naturally present real materials can lead a pocket-selective...

Quantum materials featuring both itinerant and localized degrees of freedom exhibit numerous exotic phases transitions that deviate from the Ginzburg-Landau paradigm. This work uses composite operator formalism to examine two-orbital strongly correlated Hubbard models. We observe spontaneous breaking orbital symmetry, where electron density in one orbitals reaches half-filling, resulting an orbitally selective Mott phase (OSMP). broken symmetry becomes unstable at a critical average...

Layered Nickelates have gained intensive attention as potential high-temperature superconductors, showing similarities and subtle differences to well-known Cuprates. This study introduces a modelling framework analyze the tunability of electronic structures by focusing on effective orbitals additional Fermi pockets, mimicking doping or external pressure qualitatively. It investigates role $3d_{z^2}$ orbital in interlayer hybridization, which leads formation second pocket surface. The...

We report a comparative study of two cerium-based intermetallic compounds: CeFeSi with an anti-PbFCl type structure, and CeFeSiH ZrCuSiAs structure. The latter is obtained from through hydrogen insertion. Our results are based on X-rays, transport, thermodynamic magnetic measurements. While the tetragonal structure P4/nmm symmetry remains unchanged after insertion, thermodynamic, magnetic, transport properties change drastically. On one hand, behaves as Pauli paramagnet small Sommerfeld...