4,381 research outputs found
Submodels of Nonlinear Grassmann Sigma Models in Any Dimension and Conserved Currents, Exact Solutions
In the preceding paper(hep-th/9806084), we constructed submodels of nonlinear
Grassmann sigma models in any dimension and, moreover, an infinite number of
conserved currents and a wide class of exact solutions.
In this paper, we first construct almost all conserved currents for the
submodels and all ones for the one of -model. We next review the
Smirnov and Sobolev construction for the equations of -submodel and
extend the equations, the S-S construction and conserved currents to the higher
order ones.Comment: 13 pages, AMSLaTex; an new section and an appendix adde
Gapless Excitation above a Domain Wall Ground State in a Flat Band Hubbard Model
We construct a set of exact ground states with a localized ferromagnetic
domain wall and with an extended spiral structure in a deformed flat-band
Hubbard model in arbitrary dimensions. We show the uniqueness of the ground
state for the half-filled lowest band in a fixed magnetization subspace. The
ground states with these structures are degenerate with all-spin-up or
all-spin-down states under the open boundary condition. We represent a spin
one-point function in terms of local electron number density, and find the
domain wall structure in our model. We show the existence of gapless
excitations above a domain wall ground state in dimensions higher than one. On
the other hand, under the periodic boundary condition, the ground state is the
all-spin-up or all-spin-down state. We show that the spin-wave excitation above
the all-spin-up or -down state has an energy gap because of the anisotropy.Comment: 26 pages, 1 figure. Typos are fixe
The Effect of Titanium on Microstructure and Magnetic Properties of Fe-Cr-Co Hard Magnetic Materials
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