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R. Dittrich, A. Thiaville, J. Miltat, T. Schrefl:
"Rigorous micromagnetic computation of configurational anisotropy energies in nanoelements";
Journal of Applied Physics, Vol. 93 (2003), No. 10; 7891 - 7893.

Rigorous micromagnetic computation of configurational anisotropy energies in nanoelements

Rok Dittrich
Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria

André Thiaville and Jacques Miltat
Laboratoire de Physique des Solides, Université Paris-Sud, Paris, France

Thomas Schrefl
Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria

A method combining the nudged elastic band method with finite element micromagnetics is used to calculate minimum energy paths, global minima, metastable states and, most importantly, saddle points between energy minima. We study configurational anisotropy effects in thin permalloy elements, e.g., 5 nm thick squares. For squares with the size of 15-200 nm the ground states are so-called "leaf" states with the average magnetization along one of the diagonals. However a second state ("buckle") becomes stable with the average magnetization along one edge at sizes larger than ~80 nm. The superposition of the four easy axes leads to a combination of four and eightfold anisotropy. At ~200 nm size both states have about the same energy so that the overall picture becomes that of an effective eightfold anisotropy. ©2003 American Institute of Physics.

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04970155

http://link.aip.org/link/?JAP/93/7891&agg=silverplatter