F. Strigl, in continuation of the work by J. Kimling
The deposition of Co/Pd multilayers onto self-assembled spherical particles provides a system with unique magnetic properties. The magnetic caps have high perpendicular magnetic anisotropy, are single-domain, and strongly exchange decoupled, but in electrical contact with each other, thus enabling magnetotransport measurements. By applying an external magnetic field, the caps can be switched individually. In a previous project we had measured the magnetoresistance on a two-dimensional cap array. The most prominent features could be explained with the random magnetization configuration of the magnetic caps in the demagnetized state leading to an increased spin-dependent scattering of the conduction electrons. The underlying mechanism might be comparable to the one causing giant magnetoresistance in granular alloys.
We will now concentrate on linear chains of magnetically capped colloids. This chains serve as model systems for atomic chains which can be ordered ferromagnetically or antoferromagnetically by switching the magnetization direction of the individual caps independenly.