6,484 research outputs found
B\"acklund-Darboux Transformations and Discretizations of Super KdV Equation
For a generalized super KdV equation, three Darboux transformations and the
corresponding B\"acklund transformations are constructed. The compatibility of
these Darboux transformations leads to three discrete systems and their Lax
representations. The reduction of one of the B\"acklund-Darboux transformations
and the corresponding discrete system are considered for Kupershmidt's super
KdV equation. When all the odd variables vanish, a nonlinear superposition
formula is obtained for Levi's B\"acklund transformation for the KdV equation
Topological crystalline antiferromagnetic state in tetragonal FeS
Integration between magnetism and topology is an exotic phenomenon in
condensed-matter physics. Here, we propose an exotic phase named topological
crystalline antiferromagnetic state, in which antiferromagnetism intrinsically
integrates with nontrivial topology, and we suggest such a state can be
realized in tetragonal FeS. A combination of first-principles calculations and
symmetry analyses shows that the topological crystalline antiferromagnetic
state arises from band reconstruction induced by pair checker-board
antiferromagnetic order together with band-gap opening induced by intrinsic
spin-orbit coupling in tetragonal FeS. The topological crystalline
antiferromagnetic state is protected by the product of fractional translation
symmetry, mirror symmetry, and time-reversal symmetry, and present some unique
features. In contrast to strong topological insulators, the topological
robustness is surface-dependent. These findings indicate that non-trivial
topological states could emerge in pure antiferromagnetic materials, which
sheds new light on potential applications of topological properties in
fast-developing antiferromagnetic spintronics.Comment: 8 pages, 6 figure
Flux-lattice melting in LaOFFeAs: first-principles prediction
We report the theoretical study of the flux-lattice melting in the novel
iron-based superconductor and
. Using the Hypernetted-Chain closure and an
efficient algorithm, we calculate the two-dimensional one-component plasma pair
distribution functions, static structure factors and direct correlation
functions at various temperatures. The Hansen-Verlet freezing criterion is
shown to be valid for vortex-liquid freezing in type-II superconductors.
Flux-lattice meting lines for and
are predicted through the combination of the density
functional theory and the mean-field substrate approach.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
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