Nanomagnetic logic, incorporating logic bits in the magnetization orientations of single-domain nanomagnets, has garnered attention as an alternative to transistor-based logic due to its non-volatility and unprecedented energy-efficiency. The energy efficiency of this scheme is determined by the method used to flip the magnetization orientations of the nanomagnets in response to one or more inputs and produce the desired output. Unfortunately, the large dissipative losses that occur when nanomagnets are switched with a magnetic field or spin-transfer-torque inhibit the promised energy-efficiency. Another technique offering superior energy efficiency, “straintronics”, involves the application of a voltage to a piezoelectric layer to generate a strain which is transferred to an elastically coupled magnetrostrictive layer, causing magnetization rotation. The functionality of this scheme can be enhanced further by introducing magnetocrystalline anisotropy in the magnetostrictive layer, thereby generating four stable magnetization states (instead of the two stable directions produced by shape anisotropy in ellipsoidal nanomagnets). Numerical simulations were performed to implement a low-power universal logic gate (NOR) using such 4-state magnetostrictive/piezoelectric nanomagnets (Ni/PZT) by clocking the piezoelectric layer with a small electrostatic potential (~0.2 V) to switch the magnetization of the magnetic layer. Unidirectional and reliable logic propagation in this system was also demonstrated theoretically. Besides doubling the logic density (4-state versus 2-state) for logic applications, these four-state nanomagnets can be exploited for higher order applications such as image reconstruction and recognition in the presence of noise, associative memory and neuromorphic computing. Experimental work in strain-based switching has been limited to magnets that are multi-domain or magnets where strain moves domain walls. In this work, we also demonstrate strain-based switching in 2-state single-domain ellipsoidal magnetostrictive nanomagnets of lateral dimensions ~200 nm fabricated on a piezoelectric substrate (PMN-PT) and studied using Magnetic Force Microscopy (MFM). A nanomagnetic Boolean NOT gate and unidirectional bit information propagation through a finite chain of dipole-coupled nanomagnets are also shown through strain-based "clocking". This is the first experimental demonstration of strain-based switching in nanomagnets and clocking of nanomagnetic logic (Boolean NOT gate), as well as logic propagation in an array of nanomagnets.

Submitted by Herbert João (herbertusp@gmail.com) on 2017-12-07T00:45:48Z No. of bitstreams: 1 Dissertacao Herbert_Joao.pdf: 2657068 bytes, checksum: 8fa1a3ab78779cd61ccc13237056f75b (MD5) / Rejected by Ronildo Prado (bco.producao.intelectual@gmail.com), reason: Oi , Faltou enviar a Carta comprovante assinada pelo orientador. Solicite o modelo em sua Secretaria de Pós-graduação, preencha e colete a assinatura com o orientador e acesse novamente o sistema para fazer o Upload. Fico no aguardo para finalizarmos o processo. Abraços Ronildo on 2017-12-12T11:54:01Z (GMT) / Submitted by Herbert João (herbertusp@gmail.com) on 2017-12-12T13:54:48Z No. of bitstreams: 2 Dissertacao Herbert_Joao.pdf: 2657068 bytes, checksum: 8fa1a3ab78779cd61ccc13237056f75b (MD5) Carta_comprovante_Herbert_Joao_nov2017.pdf: 201185 bytes, checksum: 81d82f7792024c746aedb98c7ab84e94 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-01-22T12:17:45Z (GMT) No. of bitstreams: 2 Dissertacao Herbert_Joao.pdf: 2657068 bytes, checksum: 8fa1a3ab78779cd61ccc13237056f75b (MD5) Carta_comprovante_Herbert_Joao_nov2017.pdf: 201185 bytes, checksum: 81d82f7792024c746aedb98c7ab84e94 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-01-22T12:17:57Z (GMT) No. of bitstreams: 2 Dissertacao Herbert_Joao.pdf: 2657068 bytes, checksum: 8fa1a3ab78779cd61ccc13237056f75b (MD5) Carta_comprovante_Herbert_Joao_nov2017.pdf: 201185 bytes, checksum: 81d82f7792024c746aedb98c7ab84e94 (MD5) / Made available in DSpace on 2018-01-22T12:18:26Z (GMT). No. of bitstreams: 2 Dissertacao Herbert_Joao.pdf: 2657068 bytes, checksum: 8fa1a3ab78779cd61ccc13237056f75b (MD5) Carta_comprovante_Herbert_Joao_nov2017.pdf: 201185 bytes, checksum: 81d82f7792024c746aedb98c7ab84e94 (MD5) Previous issue date: 2016-08-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The present work intends to produce and provide instructional material to high school teachers of physics, focusing on workshop methodology as a viable alternative to physics classes. It is proposed to equip teachers with innovative tools and context for the process of teaching-learning physics, based on the use of Information and Communication Technologies (ICT) and experimental practices. Detailed scripts were developed for the implementation of the methodology and offer of workshops in classrooms about Modern Physics (MP). From the literature it was observed that the workshops when developed with its own teachers, would make it possible to overcome deficits in their initial formation, including those regarding to the use of experimentation, technology, innovative methodologies and concepts of MP. Studies have demonstrated the real need to help teachers in the search for new alternatives for insertion of physics and its teaching in the social and technological reality of its students; As well as the effectiveness of instructional material in overcoming, even if timidly, some shortcomings with regard to pedagogical practice and the teaching of certain challenging content, in a contextualizing and motivating perspective. / O presente trabalho objetivou a produção e disponibilização de material instrucional aos professores do Ensino Médio (EM) de física, focando-se a metodologia de oficinas como alternativa viável às aulas de física. Propõe-se a instrumentalização do professor com ferramentas de inovação e de contextualização para o processo ensino-aprendizagem de física, baseada no uso das Tecnologias da Informação e Comunicação (TIC) e das práticas experimentais. Como produto foram elaborados roteiros detalhados para a implementação da metodologia e oferta das oficinas em salas de aulas sobre tópicos de Física Moderna (FM). A partir da literatura de referência observou-se que as oficinas, quando trabalhadas com os próprios professores, possibilitariam a superação de déficits na formação inicial, inclusive no que diz respeito ao uso da experimentação, da tecnologia, de metodologias inovadoras e, de conceitos em FM. Estudos tem demonstrado a necessidade real de se auxiliar os professores na busca por novas alternativas para inserção da física e do seu ensino na realidade social e tecnológica de seus alunos; assim como, a efetividade do material instrucional em suprir, mesmo que timidamente, algumas lacunas com relação à prática pedagógica e ao ensino de determinados conteúdos desafiadores, numa perspectiva contextualizadora e motivadora.