Electrically Tunable Susceptibility of Synthetic Antiferromagnet Lines

In this paper, a novel mechanism is introduced by which to modulate the permeability of a magnetic core is studied. This analysis has shown that a current passing through a coupled magnetic bilayer called a synthetic antiferromagnet (SAF) can change its effective permeability over a wide range. A key advantage of this mechanism is that SAF layers are resistant to magnetic domain formation and thus will allow high quality, low noise devices in small form factors. The electrically tunable magnetic device considered here is a magnetic thin film bilayer consisting of two ferromagnetic films (e.g. NiFe) coupled through an intervening nonmagnetic spacer layer (e.g. Cu). Description of the magnetization behavior in this coupled bilayers takes into account the effect of thickness (t), width (w), magnetization (Ms), induced anisotropy of the two layers (Ke), exchange coupling between the two layers (Ka), external magnetic field and self-field due to current flowing through the structure. With the aid of numerical calculation, the ability to induce large changes in susceptibility with reasonable current was predicted.