مرکز منطقه ای اطلاع رساني علوم و فناوري - Relation between anhysteretic and static magnetic tape parameters

Abstract :

The anhysteretic initial susceptibility $\\chi _{ar}$ of recording tape like materials is calculated from a dynamic mean field model and is given as an explicit function of the static magnetic tape parameters Ms(spontaneous magnetization of the magnetic material), $p$ (volume fraction of the magnetic material), mR(remanence to saturation ratio of the tape), and HR(remanence coercivity of the tape) for the case of particles with predominant shape anisotropy. The result, $\\chi _{ar} = frac{p(1-p) M\\min{s}\\max {2}}{2H\\min{R}\\max {2}(1-m\\min{R}\\max {2})}$ is compared with experimental data on a large number and great variety of commercial and laboratory tape samples made of γ-Fe2O3, CrO2, or Fe acicular particles covering wide ranges of all of the above parameters, and is completely verified by these data. In particular, since $H_{R}\\propto M_{s}$ for shape anisotropy, $\\chi _{ar}$ is independent of Ms, and hence of temperature $T;\\chi _{ar}$ is also independent of HRas long as the orientation mRand the particle dimensions are kept constant. Further, the above theoretical relation is remarkably insensitive against variations of the underlying model, and thus reflects the known independence of chiarupon many structural details of a material. Thus, the present theory seems to account completely for all known features of $\\chi _{ar}$ .