Magnetic properties of rare earth clusters

We report results of Stern-Gerlach deflection experiments on terbium clusters, which resemble earlier results for gadolinium clusters. As in gadolinium, we observe two distinct behaviors: clusters that are superparamagnetic and clusters that are described by a locked-moment model. The magnetic behavior is highly size dependent. Certain clusters make a transition from locked-moment to superparamagnetic behavior with increasing temperature and, in this process, exhibit an intermediate behavior. Both superparamagnetic and locked-moment clusters have magnetic moments per atom well below the bulk value. We show that oxygen atoms attached to the clusters have little effect on the clusters' magnetic properties and are not responsible for the two distinct behaviors observed in rare earth clusters. We also present preliminary results from studies on dysprosium clusters.     

A two-sided Arnoldi algorithm with stopping criterion and MIMO selection procedure

In this paper we introduce a two-sided Arnoldi method for the reduction of high order linear systems and we propose useful extensions, first of all a stopping criterion to find a suitable order for the reduced model and secondly, a selection procedure to significantly improve the performance in the multi-input multi-output (MIMO) case. One application is in micro-electro-mechanical systems (MEMS). We consider a thermo-electric micro thruster model, and a comparison between the commonly used Arnoldi algorithm and the two-sided Arnoldi is performed.     

Effect of vertical cavity mode order on surface normal coupling efficiency

The effect of the mode order of a vertical cavity surface emitting laser on the surface normal coupling efficiency into a horizontal optical waveguide is discussed. The numerical results are compared with experimental observations.