Browsing Teses e dissertações by Title

Now showing items 225-244 of 337

    • Ondas de spin em paredes de domínio unidimensionais em monocamadas magnéticas 

      Caprara, Leandro Peres (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 16/08/2012)
      Recent investigations on ferromagnetic monolayers predict the existence of spinwave modes without gap in the spectrum, even in the presence of anisotropy. These excitations propagate within the domain walls that exist in ...

    • Ondas gravitacionais e o espectro de anisotropia tensorial na presença de neutrinos cosmológicos 

      Santos, Jonas Floriano Gomes dos (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 10/07/2012)
      In this work we have studied the evolution of primordial gravitational waves coupled to anisotropic stress tensor of cosmological neutrinos. As in a radiation dominated universe, in a universe dominated by radiation and ...

    • Optical and transport properties of p-i-n GaAs/AlAs resonant tunneling diode 

      Awan, Iram Taj (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 26/05/2014)
      In this thesis, we have investigated the optical and transport properties of a p-i-n GaAs-AlAs resonant tunneling diode (RTD). The possibility of controlling and significantly varying the density of carriers accumulated ...

    • Optimal quantum control applied to quantum dots 

      Ruiz, Carlos Mario Rivera (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 03/10/2019)
      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 ...

    • Optimization and application of the quantum adiabatic theorem, and the quantum origin of classical interference 

      Souza, Paulo José Paulino de (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 29/03/2022)
      In this master’s thesis, we developed three different topics. In the first topic, we studied the quantum adiabatic brachistochrone method (QAB) for optimizing adiabatic dynamics. In the first part of this study, we reported ...

    • Ordenamento ferromagnético em poli(3-hexiltiofeno) à temperatura ambiente 

      Paula, Fernando Rogério de (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 14/07/2009)
      In this work we present, for the first time, a systematic study of magnetic properties of an alkyl derivative of thiophene: the poly(3-hexylthiophene) prepared in acetonitrile. This polymer was investigated in different ...

    • Origem dos momentos magnéticos localizados em ligas de cromo com metais de transição por oscilações de Friedel 

      Souza, Paulo Eduardo Narcizo de (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 02/08/2006)
      The fundamental magnetic properties of chromium and its alloys Cr(1¡x)Nb(x) and Cr(1¡x)V(x), were investigated with the aim to achieve a better comprehension about the nature of the spin density waves. Was dened the edge ...

    • Otimização das propriedades superficiais dos aços inoxidáveis AISI 304, AISI 316L e ASTM F138 recobertos com filme de alumínio e nitretados 

      Kapp, Mario Sergio Vinicius (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 12/03/2010)
      Many industrial applications of stainless steel require the modification of surface properties, such as corrosion resistance, and mechanical properties such as hardness. For this purpose several surface modify techniques ...

    • Otimização do controle de Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) por meio do parasitoide Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) visando a redução de custos 

      Souza, Rubens Gamaliel Bergamo de (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 26/03/2018)
      Brazil is the world’s largest producer of sugarcane. However, this agricultural crop is attacked by pests, especially Diatraea saccharalis. Its control in Brazil is carried out mainly by the action of the caterpillar ...

    • Otimização dos campos de proteção nas técnicas de desacoplamento dinâmico contínuo 

      Zanni Junior, Paulo Eduardo (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 15/09/2023)
      In this research project, we investigate the method known as \textit{continuous dynamical decoupling}, which is based on the use of continuously applied external fields to maximize the fidelity of quantum logical operations ...

    • Otimizando a eficiência de células solares baseadas em nanoestruturas semicondutoras quaternárias 

      Thomen, Diana Maria Navroski (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 28/02/2020)
      Solar cells composed of semiconductor materials with gap energies and different structures, commonly known as Multijunction, have been the record holders for efficiency in converting solar to electric energy in recent ...

    • O papel da interação elétron-elétron no regime Hall quântico interio. 

      Silva, Sanderson Francisco Fernandes Pereira da (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 02/04/2004)
      Experimental and theoretical studies of the aspects of particle-like and collective behavior of electrons in the proximity of the edges of two-dimensional (2DES) and quasi-one-dimensional (Q1DES) systems, named quantum ...

    • Passivação de superfícies de perovskitas via dopagem substitucional 

      Torres, Israel Silva (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 26/10/2023)
      Humanity currently demands new energy sources to replace polluting energy sources and thus restructure the energy matrix in a sustainable manner. In this context, materials science plays a prominent role, as new materials ...

    • Peso de Drude em anéis unidimensionais com potenciais de substituição e atravessados por fluxo magnético 

      Prado, Fabiano Oliveira (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 11/04/2002)
      In the present work the Drude weight is calculated to study the capacity of conduction at finite temperatures in one-dimensional rings with the potencial given by the sequences of different degrees of randomness and threaded ...

    • Platforms based on semiconductors for application in quantum computing 

      Cunha, Iann (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 02/06/2023)
      This thesis is composed of three parts. In the first part, a study of transport in semiconductor nanowires is carried out, in which the multichannel scattering occurs in a certain finite region, providing a reentrance in ...

    • Platforms for quantum information and technology 

      Cardoso, Fernando Redivo (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 29/02/2024)
      This work presents a collection of scientific research results in the field of quantum information. The first paper describes the mathematical properties of a particular type of state of light, called the two-mode squeezed ...

    • Polarização de spin em heteroestruturas semicondutoras contendo pontos quânticos de InAs 

      Santos, Ednilson Carlos dos (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 07/05/2010)
      In this work, we have studied spin polarization of carriers in a resonant tunneling diode GaAs/AlGaAs with InAs quantum dots in the center of the quantum well. We have observed that the photoluminescence of quantum dots ...

    • "Probabilidades negativas" e tomografia de Qubits 

      Silva, Alcenísio José de Jesus (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 28/03/2007)
      In this dissertation we approached the tomography of discrete systems, understood as the representation and the reconstruction of states. For the tomography we used distribution functions of symmetrical pseudo-probabilities. ...

    • Problema relativístico de dois corpos. 

      Hollander, Efrain Buksman (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, , 08/12/2003)
      We study the relativistic two-body problem of the action-at-a-distance electrodynamics. This dynamical system appeared 100 years ago as a time-symmetric relativistic motion and acquired the status of electrodynamics in the ...

    • Processamento convencional e assistido por campo elétrico (Flash Sintering) de cerâmicas livres de chumbo baseadas em K0,5Na0,5NbO3: propriedades físicas finais 

      Zapata, Angélica Maria Mazuera (Universidade Federal de São Carlos, UFSCar, Programa de Pós-Graduação em Física - PPGF, Câmpus São Carlos, 07/08/2020)
      K0,5Na0,5NbO3 (KNN)-based ceramics are considered promising candidates to replace lead-based piezoelectric ceramics, such as Pb(ZrxTi1−x)O3, which are widely used in electro electronic devices. However, obtaining KNN-based ...