Title :
Magnetization reversal in individual nanoparticles: macroscopic quantum tunneling of magnetization
Author :
Wernsdorfer, W. ; Orozco, E. Bonet ; Barbara, B. ; Benoit, A. ; Mailly, D. ; Demoncy, N. ; Pascard, H. ; Kubo, O. ; Nakano, H.
Author_Institution :
Lab. Louis Neel, CNRS, Grenoble, France
fDate :
7/1/1998 12:00:00 AM
Abstract :
The combination of highly sensitive Superconducting Quantum Interference Device (SQUID) with high quality nanoparticles allowed us to check for the first time simple classical models proposed nearly 50 years ago by Neel, Stoner and Wohlfarth. For nanoparticles containing about 105 to 106 μB the quantitative agreement with the Neel-Brown theory of thermal activated magnetization reversal allowed us to identify unambiguously the magnetization reversal mechanism as uniform rotation. In the case of insulating barium ferrite nanoparticles containing about 105 μB and below 0.4 K, strong deviations from this model are found which are quantitatively in agreement with the predictions of the theory of macroscopic quantum tunneling of magnetization in the low dissipation regime
Keywords :
barium compounds; ferrites; magnetic particles; magnetisation reversal; nanostructured materials; tunnelling; 0.4 K; BaFe12O19; Neel-Brown theory; SQUID; classical models; insulating barium ferrite nanoparticles; low dissipation regime; macroscopic quantum tunneling; magnetization; magnetization reversal; nanoparticles; thermal activated magnetization reversal; uniform rotation; Barium; Ferrites; Insulation; Interference; Magnetization reversal; Nanoparticles; Predictive models; Quantum mechanics; SQUIDs; Superconducting devices;
Journal_Title :
Magnetics, IEEE Transactions on
