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Mostrando ítems 21-29 de 29
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 ...
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) ...
Propriedades magneto-óticas e de magneto-transporte de um diodo de tunelamento ressonante contendo Si δ - doping no poço quântico
(Universidade Federal de São Carlos, 2011-03-11)
In this work, we have studied the transport and optical properties of GaAs = AlGaAs resonant tunneling diodes with Si delta-doping at the center of the quantum well. We have studied magneto-transport and polarized resolved ...
Domínios ferroelétricos em cerâmicas e materiais nanoestruturados: investigação por microscopia de piezoresposta
(Universidade Federal de São Carlos, 2011-12-07)
In this work, ferroelectric domain structure was investigated by Piezoresponse Force Microscopy (PFM). To this, an Atomic Force Microscope (AFM) has been modified to use it as PFM at room temperature and at high temperatures. ...
Análise de transformações de fases nas ligas Ti-35Nb-7Zr e Ti-xNb-3Fe por espectroscopia mecânica
(Universidade Federal de São Carlos, 2013-11-14)
In recent decades the study of β-Titanium alloys are attracting the interest to the biomaterials science community in general, since have improved properties as compared with current commercial biomedical alloys which ...
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze
(Universidade Federal de São Carlos, 2007-02-23)
The processing of lead metaniobate (PN) ferroelectric ceramics was optimized, therefore, in
this work, the main details to obtain PN ceramics with density higher than 96 % of the ideal density
are presented and ...
Transdutores ultra-sônicos piezoelétricos com difração limitada : simulação e construção
(Universidade Federal de São Carlos, 2006-08-18)
The importance of ultrasound limited-diffraction Bessel beams in medical
images, tissue characterization, and estimation of Doppler speed (blood flow) as
well as in many other areas of Physics has increased in the two ...
Processamento e caracterização de cerâmicas eletro-ópticas do sistema ferroelétrico (Pb1-xLax)TiO3
(Universidade Federal de São Carlos, 2006-08-04)
The ferroelectric titanate of lead modified with Lanthanum metal system (or PLT) is the most studied of the perovskite structure. It is known that ceramic bodies with specify compositions and adequately chemical preparations ...