Investigation of the effects of sample size on the coercivity of garnet films

Abstract

The coercivity of epitaxial magnetic garnet films measured by the domain-wall-oscillation methods depends on the size of the sample. It is shown that this effect is characteristic of only the wall-oscillation method. A direct, empirical correlation was found between the mechanical stresses of the sample and its magnetic parameters. It was concluded that any effect of a modification of mechanical stresses resulting from cutting of the sample can be disregarded as a possible contribution to the effect of sample size on coercivity.

Coercive Properties of Magnetic Garnet Films

“…The coercivity of LPE garnet films was measured by various methods in our work [138]. It was shown that the effect of sample size on coercivity is characteristic only of the domain wall coercivity measured by the wall oscillation method.…”

Domain-wall coercivity in ferromagnetic systems with nonuniform local magnetic field

“…In case of a single domain wall a straightforward application of an external magnetic gradient field can be used. 7 In periodic domain structures, changes of dimensions of domains by application of an external uniform field, H a , is the easiest way of influencing the field gradient G. Variation of dimensions of the sample presents another way of changing G. 9 In the present model, energy dissipation and coercivity are derived from the existence of DW Barkhausen jumps. These jumps are due to the fluctuating character of the internal DW position-restoring field, H i (x DW )ϭGx DW ϩH p (x DW ).…”

“…As a consequence of this generality, the H CW (G) dependence is likely to be responsible for such rather peculiar, not yet well described effects, like the H CW dependence on domain structure subtle features or on the size and shape of the sample, experimentally observed on various materials. 8,9 II. MODEL…”