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BASIC INTERACTIONS IN RARE EARTH MAGNETS

Objective


A study is proposed on magnetic interactions and thermo-magnetic properties of hard magnetic materials which are of technical interest. The emphasis will be on new classes of materials like the R(20)iron(14)carbon and the R iron(10)M(2)(where R is an element and M is a metal) compounds. The study of high field magnetisation and neutron scattering phenomena on R cobalt(5) and R titanium(17) are emphasised in order to deduce consistent sets of microscopic parameters by which the basic interactions in hard materials can be understood. The search for new crystal growth techniques is essential for this study.
By means of the Czochralski method single crystals of R nickel(5), with R=yttrium, lanthanum, praseodymium, neodymium, gadolinium, terbium, dysprosium, holmium and erbium have been grown. Also large single crystals of yttrium(2)iron(17), holmium(2)iron(17) and erbium(2)iron(17) have been obtained. Pseudo binary single crystals have been made of R(cobalt(1-x)nickel(x))(5), with R=yttrium, gadolinium, praseodymium. Intense field magnetisation measurements have been performed on crystals of praseodymium(nickel(x)cobalt(1-x))(5) and praseodymium nickel(5) at low temperature. Exotic behaviour is observed, associated with the crystal field level scheme of praseodymium(3+). SPD experiments have been done rare earth iron(1-x) compounds, to study the influence of small deviations from the nominal composition. A complete characterisation of the temperature dependence of the magnetic properties was carried out for R-iron-vanadium (R=yttrium, erbium, terbium). The spin reorientation transition was studied, using susceptibility measurements. The temperature dependence of the saturation magnetisation and of the rare earth and iron sublattice anisotropies were studied using a standard VSM and SPD technique respectively. The parallel and perpendicular magnetostriction in R(2)iron(14)boron and R iron(10)vanadium(2) were measured in high pulsed magnetic fields. Exchange and crystal field interactions were studied by polarised neutron diffraction measurements on dysprosium iron(11)titanium and erbium(2)cobalt(17). The moments obtained for rare earth ions are in agreement with magnetisation measurements on these materials.
A study is proposed on magnetic interactions and thermo-magnetic properties of hard magnetic materials which are of technical interest. The emphasis will be on new classes of materials like the Rd2Fe14C and the RFe10M2 compounds. The study of high-field magnetization and neutron-scattering phenomena on RCo5 and R2T17 are emphasized in order to deduce consistent sets of microscopic parameters by which the basic interactions in hard materials can be understood. The search for new crystal-growth techniques is essential for this study.

Coordinator

University of Amsterdam
Address
Valkenierstraat 65
1018 XE Amsterdam
Netherlands

Participants (3)

Centre National de la Recherche Scientifique (CNRS)
France
Address
25 Avenue Des Martyrs
38042 Grenoble
ICAM UNIVERSITY OF ZARAGOZA
Spain
Istituto Maspec Parma
Italy