NIP REPORT January 2006- May 2007 - The UP College of Science ...

nteractions between spins. With the addition of a long range interaction, it isestablished that a
one dimensional Ising short chain will have a unexpected finiteemperature phase transition.
[Tongco]
B. Multilayers Structure [Dr. C. Villagonzalo]
Giant magnetoresistance in a multilayer is due to the growth of alternately layered ferromagneticand
nonmagnetic materials. Different multilayer structures are numerically tested through abinitio
methods. The most relaxed layer combination is obtained. The structural relaxation is
observed in the lowering of the total ground state energy and in obtaining equilibrium forces on
each lattice site. [Morales, Labora]
Transport of phonons through superlattices are modeled considering harmonic and anharmonic ap
proximations. Established in these works are different layer parameters thatwill yield a reduced th
ermal conductivity. [Dizon, Parinas]
C. Transport in Low Dimensional Systems [Dr. C. Villagonzalo]
Transport in low dimensional systems in the presence of a temperature gradient or a
magnetic field is investigated. A quasione dimensional conductor model of free electrons
in the direction of propagation and confined in other directions using the relaxationtime
approximation yields a high thermal efficiency. [Muldera]
Effects of Landau level broadening usually attributed to impurities, interactions and disorder are i
nvestigated in two dimensional electron systems under strong magnetic fields and low
temperatures. Variations in the Landau level broadening yield oscillations in the chemical
potential and the heat capacity when the electron concentration is kept constant.[Gammag]
D. Modeling of Carbon Nanotubes [Dr. Villagonzalo]
A tightbinding calculation of the bandstructure of singlewalled carbon nanotubes is
utilized to determine enhancement of the thermoelectric power in these systems. [Vasquez]
E. Heat Transport [Dr. Villagonzalo]
Heat analysis in devices plays an important role in the industry of electronics, information storage
, structural applications and refrigeration. Standard Fourier law of heat transport
assumes infinite propagation speed. Taking into account a finite thermal speed, the transient
conduction of heat across a slab for varying heat sources is simulated. The focus is now on
the effect of different layer interfaces on the thermal transport properties. [De La Torre, Cortez]
F. Superconductivity [Dr. Villagonzalo]
The GinzburgLandau theory is a macroscopic model of superconductivity. A central
difference scheme for the GinzburgLandau equations is implemented to find the probability of fin
ding the superconducting electrons in a film. [Castro]
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