Mechanically induced anisotropy and its effect on magnetic permeability in single crystal ferrites

Magnetic anisotropy and initial permeability in worked Mn-Zn and Mn-Fe ferrite single crystals are investigated in connection with the average magnetostriction constant λ
s
. These data are compared with those obtained for etched specimens. Induced anisotropy is observed for all of the worked specimens and is proportional to λ
s
, i.e., its origin should be the magnetoelastic energy λσ induced by stress σ remaining in the worked specimens. The ratio of initial permeability, μ
i
(as-worked)/μ
i
(etched), at room temperature, is found to increase with increasing λ
111
in a low frequency range and to be greater than unity when |λ
111
/λ
100
|> 3. The second peak in μ
i
- T curves shifts with lapping to lower temperatures for the specimens with |λ
111
/λ
100
|<3, while to higher temperatures where |λ
111
/λ
100
|<3. Such phenomena are discussed in terms of domain wall energy affected by lapping-induced anisotropy.