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

Volume

34

Issue

4

fYear

1998

fDate

7/1/1998 12:00:00 AM

Firstpage

973

Lastpage

978

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 μ_B 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;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.706329

Filename

706329