Current Research

Three of the most important properties of magnetic materials are magnetization, Curie temperature and magnetic anisotropy. Fe and Co are very good for the first two properties but have hardly any anisotropy. From the practical point of view one needs soft magnetic materials with as little anisotropy as possible and hard magnetic materials with as high anisotropy as possible. For high anisotropy one must consider other elements such as rare-earths. We are the theoretical component of our experiment-theory group studying hard-soft magnetic and magneto-optic properties of complex materials.
First-principle self-consistent spin-polarized electronic structure calculations are carried out to determine the magnetic properties. We use the Monte Carlo method and finite-size scaling to derive the Curie temperature with results in very good agreement with the experimental data for several complex hard magnetic materials. We are doing simulation studies for exchange-coupled hard magnets which nicely complement the work being done in our experimental group. These studies have led to the identification of FePt/Fe and SmCo/Co-Fe systems as permanent-magnet materials.
We have also studied colossal magneto-resistance materials such as manganites to understand their very interesting magnetic properties. This work is supported by the National Science Foundation, U.S. Department of Energy, U.S. Air Force Office of Scientific Research and DARPA.

Recent Publications

Y. Qiang, R. F. Sabiryanov, S. S. Jaswal, Y. Liu, H. Haberland, and D. J. Sellmyer, “Magnetism of Co Nanocluster Films”, Phys. Rev. B 66, 064404 (2002).

S. H. Liou, R. F. Sabiryanov, S. S. Jaswal, J. C. Wu, and Y. D. Yao, “Magnetic Domain Patterns of Rectangular and Elliptic Arrays of Small Permalloy Elements,” J. Magn. Magn. Mater. 266-230, 1270 (2001).

R. F. Sabiryanov and S. S. Jaswal, “Magnetovolume Effect in Fe-Rich Rare-Earth Compounds: Nd₅Fe₁₇H₁₆”, J. Magn. Magn. Mater. 226-230, 1367 (2001).