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Abstract: The size dependence of magnetization reversal of magnetic tunnel junction (MTJ) rings has been investigated. The MTJ rings, with outer diameter of 4, 2 and 1μm and inner diameter of 1.5, 1 and 0.5μm were fabricated by a top–down technique. The magnetoresistance curves manifest all of the magnetic domain configurations during magnetization reversal in different sized rings. Various transition processes were observed, such as four transition, three transition and two transition in the largest, middle and smallest MTJ ring, respectively. Furthermore, the biasing fields observed from major loops decrease with decreasing size, which may result from edge roughness produced in the ion-milling process. [Copyright &y& Elsevier]

Abstract: The magnetic properties and thermal evolution of Tb0.85Na0.15MnO3− y have been studied by neutron-diffraction experiments. By comparison with the TbMnO3 sample, the results show not only small lattice parameters but also a reduction in correlation length (ξ). This is strongly correlated to the induced oxygen vacancies in Tb0.85Na0.15MnO3− y [y≈0.15(2)]. [Copyright &y& Elsevier]

We have employed ferromagnetic resonance to obtain magnetic anisotropy information in a series of YIG/GGG superlattices and a single YIG thin film with temperature variations. The Curie temperature of these samples increases with the YIG layer thickness, reaching saturation beyond a specific YIG thickness. As temperature rises, the magnitude of the calculated magnetocrystalline anisotropy constant decreases while the uniaxial anisotropy constant exhibits growing behavior. [Copyright &y& Elsevier]

We have investigated the crystal structure and magnetic properties of the new series of ordered double perovskite oxides (Sr2−xCax)FeMoO6 (0⩽x⩽1.0). A monotonous decrease of the lattice constants (a and c) has been found with increasing x. Such an effect may also give rise to a distorted structure with Fe–O–Mo angle changing from 180° for x=0 to 162° for x=1.0. The magnetization increases from x=0 to 0.5 and then slightly decreases from x=0.5 to 1.0. Such complex magnetic behavior is strongly correlated to the chemical size effect (corresponding to the internal pressure) in the title compounds. [Copyright &y& Elsevier]

Abstract: In this work, we study the preparation and properties of bio-compatible magnetic nanoparticles for immunoassay and DNA detection. The magnetite (Fe3O4) nanoparticles were prepared by a chemical co-precipitation method and dextran was selected as the surfactant to suspend the nanoparticles. Suspended particles associated with avidin followed by biotin were qualitatively analyzed by enzyme-linked immunosorbent assay (ELISA) method. We found further the ethylenediamine blocked activated residual groups efficiently, hence enhancing the attachment of biotin for probing the avidin. [Copyright &y& Elsevier]