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Showing 1 to 13 of 13 for “"Kondo lattice"”.
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Magnetic-field-induced antiferromagnetism in the Kondo lattice
The half-filled Kondo lattice model, augmented by a Zeeman term, serves as a useful model of a Kondo insulator in an applied magnetic field. A variational mean field analysis of this system on a square lattice, backed up by quantum Monte Carlo calculations, reveals an interesting separation of …
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Phase diagram for the S equals one-half and J equals three-halves Kondo lattice model
A Kondo lattice Hamiltonian for arbitrary total angular momentum J is formulated using a pseudofermion representation and without addition of RKKY interaction terms. An Hartree-Fock treatment is applied, and both variational and Green's function methods are used to calculate physical quantities …
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Electrical resistivity of the kondo systems (Ce1−xREx)In3, RE = Gd, Tb, Dy AND Ce(Pt1−xNix)Si2
… of the hybridization by substituting Ce atom in Kondo lattice CeIn3 with Gd, Tb, and Dy and by changing the chemical environment around the Ce atom in substituting Pt with Ni in CePtSi2. This thesis covers four chapters outline as follows: Chapter 1 introduces the theoretical background in rare …
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Competition and unification of Kondo coherence and magnetic ordering
… this simultaneous collapse, we study the Kondo-Heisenberg model on the honeycomb lattice at half-filling. We study a fixed point controlling the quantum phase transition of a Kondo coherent phase to a critical phase called algebraic spin liquid. Studying such a fixed point has been …
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Thermoelectric properties of mesoscopic systems in GaAs
… mesoscopic systems (2DMSs) and antidot lattices defined in them. Quantum oscillations in the thermopower (TP) of a quantum point contact allow accurate determination of the local electron temperature. The low temperature (T < 0.3 K) TP of square (5 ?m x 5 ?m) mesoscopic devices shows a …
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Density Matrix Renormalization Group Studies of Strongly Correlated Systems in Low Dimensions
… DMRG has one drawback that it cannot handle the lattices in three dimension. However, many materials with layered structure like the high-Tc superconductors can be approximated by the two dimensional lattice, and some models can be simplified or transformed into lower dimensions without losing …
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Path integral methods for the large-N Kondo model
A path integral formulation of the SU(N) Kondo model is explored as a possible theoretical tool for studying generalizations of the model, such as the Kondo lattice, which are difficult to study by other means. Saddle point approximations to the path integral lead to an expansion in powers of 1/N. …
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Development of High-Pressure Calorimetry Techniques and Calorimetry Study of the Heavy-Fermion Superconductor CeSb2
… 9T. At ambient pressure, CeSb<sub>2</sub> is a Kondo lattice heavy fermion material with a ferromagnetic ground state and various magnetic transitions at low temperatures. Between 6kbar and 16kbar, CeSb<sub>2</sub> undergoes a structural transformation that destroys the ferromagnetism, but …
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Interplay between Correlation and Topology in Two-dimensional Systems
A new class of 2d materials, moiré superlattices, has emerged and become one of the most exciting playgrounds for the study of many-body physics. These systems, thanks to their unprecedented tunability, have exhibited a plethora of interesting phenomena in experiments, such as unconventional …
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Magnetic and Structural Instabilities in Cerium Diantimonides under Pressure
… CeSb₂ and CeAgSb₂ are closely related Kondo lattice materials that are ferromagnetic at ambient pressure, unlike the majority of magnetic cerium compounds. The application of hydrostatic pressure is commonly employed to discover new phases, by continuously tuning a magnetic state, in …
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Renormalization for insulating states of matter
… the thermoelectric properties of the correlated Kondo lattice system at low temperature. Specifically, we explore the periodic Anderson impurity model with spin-orbit interactions, using the slave-particle method. As the thermopower is related to the entropy per carrier, particle-hole asymmetry …
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Flussgleichungen zur Beschreibung statischer und dynamischer Eigenschaften des eindimensionalen Kondo-Gitter-Modells
In dieser Arbeit wird das eindimensionale Kondo-Gitter-Modell untersucht, das die Wechselwirkung eines Gitters lokaler magnetischer Momente mit unkorrelierten Leitungselektronen beschreibt. Mit Hilfe der Methode der kontinuierlichen unitären Transformationen (Flussgleichungen) wird das Modell im …
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Flussgleichungen für das Anderson-Gitter zur Beschreibung von Schwer-Fermion-Systemen
In der vorliegenden Arbeit wird die Physik von Schwer-Fermion-Systemen, die durch Lanthanid- und Aktinid-Übergangsmetallverbindungen realisiert werden, untersucht. Die Basis für eine theoretische Beschreibung bildet das Anderson-Gitter, welches das Wechselspiel freier Leitungselektronen und stark …