Europhys. Lett, 48 (4), pp. 455-460 (1999)
RKKY interactions between nanomagnets of arbitrary shape
Department of Physics and Astronomy and Center for Materials Research and
University of Nebraska, Lincoln, NE 68588, USA
(received 25 May 1999; accepted in final form 21 September 1999)
PACS. 75.50Lk - Spin glasses and other random
PACS. 75.10Nr - Spin-glass and other random models.
PACS. 75.70Pa - Giant magnetoresistance.
The RKKY interaction between well-separated magnetic particles in a nonmagnetic metallic matrix is calculated. It turns out that the net interaction can be mapped onto an RKKY interaction between two point-like effective moments. The effective moments exhibit a strongly oscillating dependence on the particle's size, shape, and orientation, but their magnitudes are governed by scaling laws. As a rule, magnetostatic interactions tend to suppress the RKKY effect in particles larger than about 1 nm. Surface roughness leaves the effective-moment picture unaltered but tends to yield a moderate reduction of the effective moments. The results are discussed in the context of magnetic recording, spin-glass magnetism, and cluster physics.
Copyright EDP Sciences