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Magnetic materials

Grant number: 97/04877-0
Support type:Research Projects - Thematic Grants
Duration: October 01, 1997 - September 30, 2000
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal Investigator:Frank Patrick Missell
Grantee:Frank Patrick Missell
Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated grant(s):99/10208-9 - 1) magnetic properties and underlayer thickness in of smco/cr films. 2) preisach analysis of reversible magnetization in smco/fe films 3) annealing dependence of gmr in cufeni alloys., AR.EXT
99/10209-5 - Structural and magnetic properties of exchange-coupled prfeb alloys., AR.EXT


We are proposing the study of different types of magnetic materials, but principally magnetically hard materials involving alloys of rare earth transition-metals. In well characterized magnets of SmCo5, we intend to determine if the field of anisotropy is affected by alterations in the composition of the matrix caused by thermal treatments. To know that the intrinsic properties of Nd2Fe14B are influenced by the grain size of the material, we need to determine if this compound is stoichiometric or not. In nanocrystalline alloys of SmFeCo and PrFeB, we intend to study the problem of separating reversible magnetization from the irreversible and the consequences for determination of the magnetic viscosity. We will undertake a magnetic characterization of hybrid magnets, composed of powders of ferrite and MQP-Q, agglomerated with a resin, to understand better the grain interactions. We will make thin films of SmCo, NdFeB, and SmFeCo to study interactions between grains using techniques developed for magnets. In the study of the interactions we have two powerful tools at our disposal: the Preisach model and micromagnetic simulations using a Metropolis-Monte Carlo algorithm. We intend to implant magnetic force microscopy (MFM) and to use this technique in the study of hybrid magnets and electric steels. Studies of giant magnetoresistance (GMR) in alloys of Cu-Co, Cu-Fe-Ni, and Au-Co could benefit from our experience with Henkel plots. Finally we intend to study losses and permeability in electric steels and relate these values with the microstructure. In summary, all the subprojects mentioned here involve the theoretical and/or experimental study of interacting magnetic entities. The experience accumulated during the last few years in dealing with this type of problem means that we have the possibility of making relevant contributions in various areas of magnetism. (AU)