Related papers: Magnetic quantum phase transition in a metallic Ko…
We study the isotropic Heisenberg chain with nearest and next-nearest neighbour interactions. The ground state phase diagram is constructed in dependence on the additonal interactions and an external magnetic field. The thermodynamics is…
We study the coupled-top model with three large spins located on a triangle. Depending on the coupling strength, there exist three phases: disordered paramagnetic phase, ferromagnetic phase, and frustrated antiferromagnetic phase, which can…
How many magnetic moments periodically arranged on a metallic surface are needed to generate a coherent Kondo lattice behavior? We investigate this fundamental issue within the particle-hole symmetric Kondo lattice model using quantum Monte…
Effects of electron correlations on Anderson insulators have been one of the central themes for recent two decades, suggesting that the Anderson insulating phase turns into a novel insulating state referred to as many body localization…
We study two-dimensional Heisenberg antiferromagnets with additional multi-spin interactions which can drive the system into a valence-bond solid state. For standard SU(2) spins, we consider both four- and six-spin interactions. We find…
We propose a novel random matrix model that describes the QCD Kondo phase. The model correctly implements both the chiral symmetry of light quarks and the SU(2) spin symmetry of heavy quarks. We analytically take the large-N limit with N…
We study a pseudogap Anderson-Holstein model of a magnetic impurity level that hybridizes with a conduction band whose density of states vanishes in power-law fashion at the Fermi energy, and couples, via its charge, to a nondispersive…
We study the fate of a spin-1/2 impurity in the itinerant antiferromagnetic metallic phase via a renormalization group analysis and a variational calculation. The local moment - conduction electron interaction hamiltonian in an…
Systems with strong spin orbit coupling support a number of new phases of matter and novel phenomena. This work focuses on the interplay of spin orbit coupling and interactions in yielding correlated phenomena in two dimensional transition…
The nature of magnetic order and transport properties near surfaces is a topic of great current interest. Here we model metal-insulator interfaces with a multi-layer system governed by a tight-binding Hamiltonian in which the interaction is…
A novel approach for studying phase transitions in systems with quantum degrees of freedom is discussed. Starting from the microscopic hamiltonian of a quantum model, we first derive a set of exact differential equations for the free energy…
We study the critical properties in cubic systems of antiferromagnetically coupled spin dimers near magnetic-field induced quantum phase transitions. The quantum critical points in the zero-temperature phase diagrams are determined from…
We develop an analytical approach based on a unitary transformation to investigate S=1/2 antiferromagnetic Heisenberg chains coupled to phonons, and find a new quantum phase transition at zero temperature. Although the usual phase…
We study the quantum phase diagram of the Heisenberg planar antiferromagnet with a subset of four-spin ring exchange interactions, using the recently proposed heirarchical mean-field approach. By identifying relevant degrees of freedom, we…
Motivated by the proposal of topological quantum paramagnet in the diamond lattice antiferromagnet NiRh$_2$O$_4$, we propose a minimal model to describe the magnetic interaction and properties of the diamond material with the spin-one local…
We study quantum ferrimagnets in one, two, and three dimensions by using a variety of methods and approximations. These include: (i) a treatment based on the spin coherent state path-integral formulation of quantum ferrimagnets by taking…
We present a detailed numerical study of spin and charge dynamics of the two-dimensional Kondo lattice model with hopping t and exchange J. At T=0 and J > 0, the competition between the RKKY interaction and Kondo effect triggers a quantum…
In heavy-fermion systems, the competition between the local Kondo physics and intersite magnetic fluctuations results in unconventional quantum critical phenomena which are frequently addressed within the Kondo lattice model (KLM). Here we…
The Quantum Monte-Carlo simulations of the two-dimensional Hubbard model are presented for the half filling. The method based on the direct-space proposed by Suzuki and al., and Hirsch and al. was used. The states generated by this method…
We study the finite size effect of the Kondo screening cloud in a double-quantum-dot setup via a large-N slave-boson mean-field theory. In this setup, one of the dots is embedded in a close metallic ring with a finite size $L$ and the other…