Magnetic microstructure and range of critical magnetic correlations in nanocrystalline gadolinium

• Applicant: Professor Dr. Andreas Michels
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2006 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 24982846

We will study the influence of internal interfaces (grain and phase boundaries) on the Curie transition and on the magnetic microstructure of nanocrystalline bulk gadolinium and nanocrystalline gadolinium alloys. High-quality nanocrystalline bulk gadolinium samples can now be prepared by the inert-gas condensation technique, and their magnetic properties will be investigated by means of magnetometry, specific-heat measurements, neutron diffraction, and in particular by measurements using magnetic small-angle neutron scattering on the low-capturing isotope 160gadolinium. Magneticfield dependent small-angle neutron scattering in conjunction with the theory of micromagnetics is a novel approach which allows one to determine the set of intrinsic interaction parameters of a ferromagnet such as exchange constant, anisotropy field, stray field, and a characteristic length of spin misalignment. By alloying nanocrystalline gadolinium with the highly anisotropic rare-earth metal terbium, we aim at tailoring increasing magnetic anisotropy and study its effect on the magnetic interactions. Furthermore, we propose to study the effect of grain-boundary chemistry on the magnetic behavior by alloying nanocrystalline gadolinium with the nonmagnetic element tantalum which exhibits a strong tendency to interfacial segregation. In particular, by varying the tantalum interfacial excess concentration, we are able to study the mechanism of exchange coupling across grain boundaries.

• DFG Programme: Research Grants
• International Connection: Luxembourg
• Participating Person: Professor Dr. Rainer Birringer