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Master's Dissertation
DOI
10.11606/D.76.2017.tde-08032017-091450
Document
Author
Full name
José Felix Estanislau da Silva
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2001
Supervisor
Committee
Menezes, Jose Carlos Egues de (President)
Barbosa, José Camilo
Castro, José D'Albuquerque e
Title in Portuguese
Shot Noise e corrente dependentes de spin: modelo quântico
Keywords in Portuguese
Correntes spin polarizadas
Flutuações
Semicondutor
Shot noise
Transporte dependente de spin
Abstract in Portuguese
Nesta dissertação, fazemos a primeira investigação sobre flutuações em corrente e corrente média dependentes de spin em potenciais duplo e simples da estrutura Zn1-xMnxSe. Consideramos efeitos de campos magnético e elétrico externos à temperatura nula. Na presença de um campo magnético, a interação dos íons de Mn com elétrons de condução e valência (interação de troca sp-d) origina potenciais dependentes de spin para o transporte em Zn1-xMnxSe. Aqui, flutuações em corrente ("shot noise") e a corrente média são calculados usando o modelo quântico de transporte através do potencial dependente de spin é descrito por uma matriz s de espalhamento. Os elementos da matriz de espalhamento, i.e., as amplitudes de transmissão e reflexão, são determinados pelo método da matriz transferência. Nossos resultados indicam que estruturas de potenciais simples e duplos Zn1-xMnxSe agem como se fossem "filtros de spin" para corrente. Em determinadas faixas de parâmetros do sistema, "shot noise" pode complementar informações obtidas da corrente média
Title in English
Shot noise and spin-dependent currents: a quantum model
Keywords in English
Non-equilibrium current
Shot noise
Spin dependent transport
Spin-polarized current
Abstract in English
In this dissertation we investigation for the first time spin dependent-current and its fluctuations in double and single barrier potentials of the Zn1-xMn xSe structure sandwiched between ZnSe layers. We consider effects of external magnetic field, the interaction of the Mn ions with thew conduction and valence electrons (sp-d exchange interation) give rises to spin-dependent potentials for transport across the Zn1-xMn xSe layer. Here, the average current and its fluctuations are calculated using the quantum transport model in which transport across the spin-dependent potential is described via scattering matrix s. The elements of the scattering matrix, i.e., the transmission and reflection amplitudes, are determined through the transfer-matrix method. Our results indicate date single and double potentials of the Zn1-xMn xSe structure act as "spin filters" for the current. Within some system parameter range, shot noise can supplement the information contained in the average current
 
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Publishing Date
2017-03-20
 
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