The values of saturation magnetization ([M.sub.s]), retentivity (Mr), coercivity (Hc) and squareness ratio S =([M.sub.r]/[M.sub.s]) are presented in Table 4.
The squareness ratio (S) of the sample with x = 0.10 is 0.00006 which indicates a superparamagnetic behavior.
Stoichiometric particles (C)% ratio Metal : Ba Ba 3.84 1.00 1.00 Fe 30.87 8.04 8.00 Cu 2.54 0.66 0.53 Mn 0.40 0.10 0.13 O 62.36 16.2 13.7 Table 3: Saturation magnetization ([M.sub.s]), remanence ([M.sub.r]), squareness ratio
[M.sub.rs] (= [M.sub.r]/[M.sub.s]), coercive field ([H.sub.c]), anisotropy field ([H.sub.a]), initial susceptibility ([x.sub.i]), and initial permeability ([[mu].sub.i]) for the [Ba.sub.3][[Cu.sub.0.8-x][Zn.sub.x][[Mn.sub.0.2]].sub.2] [Fe.sub.24][O.sub.41] (x = 0.0-0.8) samples.
Generally, the various types of magnetization curves (with large or small squareness ratio
) can be obtained after annealing in longitudinal or transverse magnetic fields (O'Handley, 1999).
A common way to quantify the shape of the curve is to use a parameter termed squareness factor (SF) (or in some papers squareness ratio
The increased squareness ratio
([M.sub.r]/[M.sub.s]) in this case as well favors the use of these materials for the applications where high energy products are desired.
As shown in Figure 4, the formations of an array of nanowires under (a) parallel and (b) perpendicular magnetic fields at room temperature are measured for their magnetic properties such as coercive force and squareness ratio (remanence magnetization/saturation magnetization).
They have greater squareness ratio of about 64.2% under the parallel external magnetic field, whereas it is only about 14.20% under the perpendicular magnetic field.
The magnetic properties such as saturation magnetization ([M.sub.s]), coercivity ([H.sub.c]), retentivity ([M.sub.r]), and squareness ratio
were calculated from the hysteresis data and tabulated in Table 2.