Search results for "Diagram"
showing 10 items of 795 documents
The inhomogeneous phase of dense skyrmion matter
2019
It was predicted qualitatively in ref.[1] that skyrmion matter at low density is stable in an inhomogeneous phase where skyrmions condensate into lumps while the remaining space is mostly empty. The aim of this paper is to proof quantitatively this prediction. In order to construct an inhomogeneous medium we distort the original FCC crystal to produce a phase of planar structures made of skyrmions. We implement mathematically these planar structures by means of the 't Hooft instanton solution using the Atiyah-Manton ansatz. The results of our calculation of the average density and energy confirm the prediction suggesting that the phase diagram of the dense skyrmion matter is a lot more comp…
Finite temperature phase diagram of a polarized Fermi gas in an optical lattice
2007
We present phase diagrams for a polarized Fermi gas in an optical lattice as a function of temperature, polarization, and lattice filling factor. We consider the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO), Sarma or breached pair (BP), and BCS phases, and the normal state and phase separation. We show that the FFLO phase appears in a considerable portion of the phase diagram. The diagrams have two critical points of different nature. We show how various phases leave clear signatures to momentum distributions of the atoms which can be observed after time of flight expansion.
Entanglement Properties and Phase Diagram of the Two-Orbital Atomic Hubbard Model
2009
We study the two-orbital Hubbard model in the limit of vanishing kinetic energy. The phase diagram in the $V-J$ plane, with $V$ and $J$ denoting the interorbital hybridization and exchange coupling respectively, at half filling is obtained. A singlet(dimer)-triplet transition is found for a critical value of the ratio $V/J.$ The entropy of formation, both in the mode and in the particle picture, presents a jump as the same critical line in conformity with the suggested relation between criticality and entanglement.
The Ising model as a playground for the study of wetting and interface behavior
2000
Computer simulations have played an important role in the elucidation of wetting and interface unbinding phenomena. In particular, use of the Ising-lattice-gas model in a film geometry and subject to diverse surface and bulk magnetic fields has permitted extensive Monte Carlo simulations to reveal new features of the phase diagrams associated with these phenomena and to provoke new theoretical studies. The status of our knowledge about the nature of wetting and interface-delocalization transitions which has resulted from these Ising model simulations will be summarized.
Quantum Dots in Magnetic Fields: Phase Diagram and Broken Symmetry at the Maximum-Density-Droplet Edge
1999
Quantum dots in magnetic fields are studied within the current spin-density-functional formalism avoiding any spatial symmetry restrictions of the solutions. We find that the maximum-density droplet reconstructs into states with broken internal symmetry: The Chamon-Wen edge coexists with a modulation of the charge density along the edge. The phase boundaries between the polarization transition, the maximum-density droplet, and its reconstruction are in agreement with recent experimental results.
Magnetic order in the heavy fermion system Ce(Cu1−xNix)2Ge2
1990
Abstract The magnetic phase diagram of the heavy fermion (HF) systems Ce(Cu 1−x Ni x ) 2 Ge 2 is discussed utilizing results of transport, thermodynamic and neutron-scattering measurements. While the Kondo temperature increases monotonically with x, a complex x-dependence is found for the Neel temperature, associated with a transition from local-moment to itinerant HF magnetism.
Revisiting spin cycloids in multiferroic BiFeO3
2018
We revisit the inverse spin current model that has been previously used to explain the existence of magnetic cycloids in bulk multiferroic ${\mathrm{BiFeO}}_{3}$. Using a first-principles-based effective Hamiltonian method, and in combination with Monte Carlo simulations, we predict a magnetic phase diagram as a function of first- and second-nearest-neighbor interaction strength in the spin current model and show that, in contrast with previous understanding, both first and second nearest neighbors have to be taken into account to be in accordance with experimental findings, including the existence of type-1 and type-2 cycloids with, respectively, $[1\overline{1}0]$ and $[11\overline{2}]$ p…
Interface localisation-delocalisation transition in a symmetric polymer blend: a finite-size scaling Monte Carlo study
2001
Using extensive Monte Carlo simulations we study the phase diagram of a symmetric binary (AB) polymer blend confined into a thin film as a function of the film thickness D. The monomer-wall interactions are short ranged and antisymmetric, i.e, the left wall attracts the A-component of the mixture with the same strength as the right wall the B-component, and give rise to a first order wetting transition in a semi-infinite geometry. The phase diagram and the crossover between different critical behaviors is explored. For large film thicknesses we find a first order interface localisation/delocalisation transition and the phase diagram comprises two critical points, which are the finite film w…
Ideal glass transitions for hard ellipsoids
2000
For hard ellipsoids of revolution we calculate the phase diagram for the idealized glass transition. Our equations cover the glass physics in the full phase space, for all packing fractions and all aspect ratios X$_0$. With increasing aspect ratio we find the idealized glass transition to become primarily be driven by orientational degrees of freedom. For needle or plate like systems the transition is strongly influenced by a precursor of a nematic instability. We obtain three types of glass transition lines. The first one ($\phi_c^{(B)}$) corresponds to the conventional glass transition for spherical particles which is driven by the cage effect. At the second one ($\phi_c^{(B')}$) which oc…
Universal behavior of two-dimensional 3He at low temperatures.
2008
On the example of two-dimensional (2D) 3He we demonstrate that the main universal features of its experimental temperature T - density x phase diagram [see M. Neumann, J. Ny\'{e}ki, J. Saunders, Science 317, 1356 (2007)] look like those in the heavy-fermion metals. Our comprehensive theoretical analysis of experimental situation in 2D 3He allows us to propose a simple expression for effective mass M^*(T,x), describing all diverse experimental facts in 2D 3He in unified manner and demonstrating that the universal behavior of M^*(T,x) coincides with that observed in HF metals.