10 research outputs found
Surface Incommensurate Structure in an Anisotropic Model with competing interactions on Semiinfinite Triangular Lattice
An anisotropic spin model on a triangular semiinfinite lattice with
ferromagnetic nearest-neighbour interactions and one antiferromagnetic
next-nearest-neighbour interaction is investigated by the cluster
transfer-matrix method. A phase diagram with antiphase, ferromagnetic,
incommensurate, and disordered phase is obtained. The bulk uniaxial
incommensurate structure modulated in the direction of the competing
interactions is found between the antiphase and the disordered phase. The
incommensurate structure near the surface with free and boundary condition
is studied at different temperatures. Paramagnetic damping at the surface and
enhancement of the incommensurate structure in the subsurface region at high
temperatures and a new subsurface incommensurate structure modulated in two
directions at low temperatures are found.Comment: 13 pages, plainTex, 11 figures, paper submitted to J. Phys.
Incommensurate structures studied by a modified Density Matrix Renormalization Group Method
A modified density matrix renormalization group (DMRG) method is introduced
and applied to classical two-dimensional models: the anisotropic triangular
nearest- neighbor Ising (ATNNI) model and the anisotropic triangular
next-nearest-neighbor Ising (ANNNI) model. Phase diagrams of both models have
complex structures and exhibit incommensurate phases. It was found that the
incommensurate phase completely separates the disordered phase from one of the
commensurate phases, i. e. the non-existence of the Lifshitz point in phase
diagrams of both models was confirmed.Comment: 14 pages, 14 figures included in text, LaTeX2e, submitted to PRB,
presented at MECO'24 1999 (Wittenberg, Germany
Steady one-dimensional thermal flow in an -body system with internal heat generation. I
summary:Under certain conditions, the termal flow in an -body system may be considered as onedimensional. The paper presents a generla formulation and a general solution of this problem