Navegação por Assunto "Antiferromagnetismo"
Resultados 1-19 de 19
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Algebraic properties of the bethe ansatz for an spl(2,1)-supersymmetric t-j model
(1993) [Artigo de periódico]We investigate the algebraic structure of the supersymmetric t−J model in one dimension. We prove that the Bethe ansatz states are highest-weight vectors of an spl(2,1) superalgebra. By acting with shift operators we ... -
Antiferromagnetism and spin glass in a Kondo lattice
(2004) [Resumo publicado em evento] -
Comparison of computed amplitudes of magnetoresistance in spin-valve structures with wafer probe measurements
(1998) [Artigo de periódico]A code has been developed based on the semi-classical theory of giant magnetoresistance of Camley and Barnas [l]. It computes the sheet conductance and magnetoresistance of spin-valve structures. The input parameters are ... -
Controle de fase do Exchange Bias em filmes de Co/IrMn/Cu/Co
(2010) [Dissertação]Tratamentos térmicos e irradiações com íons He+ foram utilizados para controle do Exchange Bias, EB, em filmes finos de Co/IrMn/Cu/Co. Enquanto a direção do campo magnético aplicado durante o tratamento foi variada, as ... -
Controlled rotation of the exchange-bias direction in IrMn/Cu/Co via ion irradiation
(2008) [Artigo de periódico]Co/Cu/IrMn films were irradiated with 40 keV He+ ions varying the fluence and the current, with magnetic field applied at 120° with respect to the original exchange-bias direction. The angular variations of the exchange-bias ... -
Doping dependence of the electronic structure and magnetic order in high-tc superconductors
(1994) [Artigo de periódico]The local densities of states of an extended Hubbard model describing the Cu02 planes of superconducting cuprates are calculated by means of an approximate treatment that divides the lattice into Cu02 clusters. The exact ... -
Effect of band filling in the Kondo lattice : a mean-field approach
(1999) [Artigo de periódico]The usual Kondo lattice, including an antiferromagnetic exchange interaction between nearest-neighboring localized spins, is treated here in a mean-field scheme that introduces two mean-field parameters: one associated ... -
Estudo de interações hiperfinas nos compostos (Co1-xFex)Co3 por espectroscopia Mössbauer do 57Fe
(1976) [Dissertação]Espectroscopia Mössbauer foi usada para investigar as propriedades magnéticas dos compostos antiferromagnéticos CO1-xFexCO3 com x= 0,01, 0,05, 0,1 e 0,3 à temperatura de 4,2 °K, abaixo da temperatura de Néel. As interações ... -
Exchange bias em filmes policristalinos : estudo da importância dos spins de interface e de volume do antiferromagneto
(2011) [Dissertação]O presente estudo traz uma discussão sobre a modificação dos parâmetros de EB através de tratamentos térmicos em filmes de IrMn/Cu(0,25 nm)/Co e IrMn/Co deposi-tados por sputtering. A temperatura de recozimento foi variada ... -
Impact of magnetization easy-axis distributions on the ferromagnet-antiferromagnet exchange-coupling estimation
(2008) [Artigo de periódico]It is frequently reported that different measurement techniques may yield distinct values for the exchange anisotropy, being the difference of up to one order of magnitude on comparing magnetization loop with ac susceptibility ... -
A influência de uma camada magneticamente macia em filmes finos que apresentam exchange bias
(2012) [Trabalho de conclusão de graduação]Este trabalho reúne medidas de magnetização e de difratometria de raios-x com o objetivo de realizar a caracterização magnética e estrutural de amostras magnéticas. As amostras são filmes finos compostos por IrMn (7 nm) / ... -
Modificação da anisotropia magnética através de feixes de íons
(2011) [Trabalho de conclusão de graduação]Exchange Bias (EB), onde serão estudadas as mudanças ocorridas quando submetidos a tratamentos térmicos e processos de irradiação iônica. Foi dada ênfase na influência do tratamento nas mudanças geradas pela irradiação. A ... -
Nature of insulating state in the three-band hubbard model : a tight-binding approach
(1995) [Artigo de periódico]We study the three-band Hubbard model, commonly used to describe the copper-oxygen planes of high-Tc superconductors, from the point of view of electronic properties. Utilizing perturbation theory around the atomic limit ... -
Nematic phase in two-dimensional frustrated systems with power-law decaying interactions
(2013) [Artigo de periódico]We address the problem of orientational order in frustrated interaction systems as a function of the relative range of the competing interactions. We study a spin model Hamiltonian with short-range ferromagnetic interaction ... -
Numerical renormalization-group study of the correlation functions of the antiferromagnetic spin 1/2 Heisenberg chain
(1995) [Artigo de periódico]We use the density-matrix renormalization-group technique developed by White to calculate the spin correlation functions (S2n+I S2n)=(-1) 1 w(l,N) for isotropic Heisenberg rings up to N=70 sites. The correlation functions ... -
Revisited doniach diagram : influence of short-range antiferromagnetic correlations in the Kondo lattice
(1997) [Artigo de periódico]The Kondo lattice model including nearest-neighbor magnetic exchange interactions is studied here in a mean-field approximation describing both the Kondo state and the intersite magnetic correlations. In the case of ... -
Rotatable anisotropy and coercivity in exchange-bias bilayers
(2002) [Artigo de periódico]A phenomenological approach for polycrystalline exchange-bias bilayers is proposed which explains the coercivity enhancement as well as its temperature and coupling strength dependences. In the model, it is assumed that ... -
Spin liquid versus long-range magnetic order in the frustrated body-centered-tetragonal lattice
(2016) [Artigo de periódico]We show how spin-liquid (SL) states can be stabilized in a realistic three-dimensional model as a result of frustration. SU(n)-symmetric generalization of the Heisenberg model for quantum spin S operators is used to ... -
Uso de curvas de remanência magnética em sistemas que apresentam exchange-bias
(2013) [Trabalho de conclusão de graduação]O presente estudo discute a adaptação e a elaboração de uma técnica que usa medidas de remanência magnética em sistemas que apresentam interação de troca, visando a extração de resultados referentes a interações magnéticas ...