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Now showing items 141-150 of 186
Efeitos de spin em diodos de tunelamento ressonante tipo-p
(Universidade Federal de São Carlos, 2012-03-27)
In this work, we have investigated the spin effects in p-i-p GaAs/AlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. The spin-dependent tunneling of carriers was studied by analyzing the ...
Simulações de líquidos super-resfriados via dinâmica molecular
(Universidade Federal de São Carlos, 2012-10-15)
This work presents the study of two models of glass-forming liquids using molecular dynamics simulations. The first model aims to analyze the effects on glassy dynamics which allow the enhancement of the glass formability ...
Propriedades de transporte de spins polarizados em heteroestruturas semicondutoras
(Universidade Federal de São Carlos, 2009-06-25)
In this work we used the technique of scattering matrix to calculate the transmissivity of polarized spins in a semiconductor symmetrical double-barrier heterostruture. The dynamics of carriers is described by effective ...
Estrutura de platô na magnetização em modelos de spins frustrados
(Universidade Federal de São Carlos, 2012-10-26)
This thesis study the phase transition, forms classical and quantum models of spin frustration. The Heisenberg model of spin 1/2 with exchange anisotropy with competitive interactions between first (J1) and second (J2) ...
Estudo de primeiros princípios das propriedades eletrônicas de novos materiais derivados do grafeno : as nanofitas e nanofios
(Universidade Federal de São Carlos, 2012-09-05)
In this thesis, we study new materials derived from graphene, like nanowires and nanoribbons, with numerical calculations based on the density functional theory (DFT) and the non-equilibrium Green functions (NEGF). We will ...
Flux avalanches in patterned superconducting thin films: ac susceptibility, morphology and related studies
(Universidade Federal de São Carlos, 2013-04-12)
Avalanches are sudden dramatic phenomena that occur in nature. The technique of magneto-optical imaging (MOI) has allowed us to observe abrupt flux entrances in superconductors, the so-called ux avalanches, due to ...
Processos Paramétricos em eletrodinâmica quântica de cavidades.
(Universidade Federal de São Carlos, 2004-03-02)
In this thesis we study the interaction between an atom and a cavity mode submitted
to linear and parametric amplifications. The evolution operator of the system was derived
through the technique of time-dependent ...
Controle das propriedades estatísticas do campo e biestabilidade óptica em eletrodinâmica quântica de cavidades
(Universidade Federal de São Carlos, 2013-03-27)
We investigate in this thesis the control of absorptive optical bistability in a standing wave optical cavity filled with a collection of two and three-level noninteracting atoms weakly coupled to a single electromagnetic ...
Vidros: sólidos ou líquidos? Uma análise via simulação computacional
(Universidade Federal de São Carlos, 2019-10-10)
For many centuries there were different definitions of what glass would be, this discussion
persists to current days. Is glass a solid or liquid material? In this work, we answer this question
through computational ...
Optimal quantum control applied to quantum dots
(Universidade Federal de São Carlos, 2019-10-03)
In the present study, we review the one-qubit dynamics and we offer a new unifying interpretation of the Landau-Zenner and the Rabi dynamics, by indicating the physical elements responsible for the manifestation of one ...