62,308 research outputs found
Monte Carlo Study of the Spin-1 Baxter-Wu Model
The two-dimensional spin-1 Baxter-Wu model is studied by using Monte Carlo
simulations. The standard single-spin-flip Metropolis algorithm is used to
generate the configurations from which the order parameter, specific heat and
magnetic susceptibility are measured. The finite-size scaling procedure is
employed in order to get the critical behavior. The extensive simulations shown
that the critical exponents are different from those of the spin-1/2 model
suggesting that the spin-1 model is in a different universality class.Comment: 3 pages, 3 figures, 1 tabl
Zero-temperature TAP equations for the Ghatak-Sherrington model
The zero-temperature TAP equations for the spin-1 Ghatak-Sherrington model
are investigated. The spin-glass energy density (ground state) is determined as
a function of the anisotropy crystal field for a large number of spins.
This allows us to locate a first-order transition between the spin-glass and
paramagnetic phases within a good accuracy. The total number of solutions is
also determined as a function of .Comment: 11 pages, 2 ps figures include
Superlens made of a metamaterial with extreme effective parameters
We propose a superlens formed by an ultra-dense array of crossed metallic
wires. It is demonstrated that due to the anomalous interaction between crossed
wires, the structured substrate is characterized by an anomalously high index
of refraction and supports strongly confined guided modes with very short
propagation wavelengths. It is theoretically proven that a planar slab of such
structured material makes a superlens that may compensate for the attenuation
introduced by free-space propagation and restore the subwavelength details of
the source. The bandwidth of the proposed device can be quite significant since
the response of the structured substrate is non-resonant. The theoretical
results are fully supported by numerical simulations.Comment: Accepted for publication in Phys. Rev. B (in press
Spin waves in ultrathin ferromagnetic overlayers
The influence of a non-magnetic metallic substrate on the spin wave
excitations in ultrathin ferromagnetic overlayers is investigated for different
crystalline orientations. We show that spin wave dumping in these systems occur
due to the tunneling of holes from the substrate into the overlayer, and that
the spin wave energies may be considerably affected by the exchange coupling
mediated by the substrate.Comment: RevTeX 4, 7 pages, 5 figures; submitted to Phys. Rev.
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