Spin switching phase diagram of mesoscopic ring magnets

In this paper we present the switching phase diagram and the switching field trends of mesoscopic NiFe and Co rings. The type of switching (single, double, triple) is systematically identified from the hysteresis loop for different values of the important geometrical parameters (outer diameter, ring width and film thickness). The switching fields are determined and the evolution with varying geometry is studied for a wide range of parameters (outer diameter D: 90 nm-4μm, ring width W: 10-90% of D and film thickness t: 2-42 nm). The trends observed are explained in terms of the different physical processes occurring during the transitions (e.g. domain wall depinning, propagation, nucleation). By adjusting the ring geometry, the switching fields can be tailored over a wide range of values spanning more than an order of magnitude.