Magnetic switching and anisotropy in nanomagnets: the influence of size and shape

Arrays of nanomagnets were fabricated out of Ni80Fe14Mo5 in the lateral size range 500-30nm and the thickness range 3-20nm. Elliptical, triangular, square, pentagonal and circular geometries were all considered. The magnetic properties of these nanomagnets were probed rapidly and non-invasively using a high sensitivity magneto-optical method.

Magnetization process of a single chain of nanomagnets

We have investigated the magnetization reversal process of a single chain of identical nanomagnetic dots fabricated from 30 nm thick Ni 80Fe20. The structures consist of two 5 μm wide support wires bridged with a single chain of identical dots of diameter δ in the range 100-250 nm. For fields applied perpendicular to the single chain, we observed an unusual size dependent hysteretic behavior in the magnetoresistance curve at high field. This is due to the magnetostatic interaction arising from the proximity of the magnetic charges. We are able to deduce from a simple micromagnetic simulation that the reversal process in the chain of dots with δ=100nm is mediated by a collective process of nearly coherent spin rotation. The magnetotransport measurements along the chain reveal a complex magnetization reversal process in the chain of nanomagnets. © 2002 American Institute of Physics.