2007/05/02 by Lin He, Chinping Chen
Materials Science · Physics and Astronomy · #Magnetic Properties and Applications #Magnetic Properties of Alloys #Magnetic properties of thin films #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.75.184424
published as Phy. Rev. B 75, 184424 (2007) · 22 pages, 2 figures, 1 table, Accepted by Phys. Rev. B
arxiv created 2007/05/02 · openalex publication_date 2007/05/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The temperature variation effect of shape anisotropy on the coercivity, HC(T), for the aligned Stoner-Wohlfarth (SW) soft ferromagnets, such as fcc Ni, fcc Co, and bcc Fe, are investigated within the framework of N'eel-Brown (N-B) analysis. An extended N-B equation is thus proposed, HC(T)=H0m(\ensuremathτ)1\ensuremath-[\frackBT\phantom\rule0.2em0exln(t∕t0)E0m2(\ensuremathτ)]^1∕\ensuremathα, by introducing a single dimensionless correction function, the reduced magnetization, m(\ensuremathτ)=MS(T)∕MS(0), in which \ensuremathτ=T∕TC is the reduced temperature, MS(T) is the saturation magnetization, and TC is the Curie temperature. The factor, m(\ensuremathτ), accounts for the temperature-dependent effect of the shape anisotropy. The constants, H0 and E0, are for the switching field at zero temperature and the potential barrier at zero field, respectively. According to this newly derived equation, the blocking temperature above which the properties of superparamagnetism show up is described by the expression, TB=E0m2(\ensuremathτB)∕[kB\phantom\rule0.2em0exln(t∕t0)], with the extra correction factor m2(\ensuremathτB). The possible effect on HC(T) and the blocking temperature, TB, attributed to the downshift of TC resulting from the finite size effect has been discussed also.