Planar Hall effect sensors with shape-induced effective single domain behavior

We show that shape anisotropy induces effective single domain behavior in elliptical structures of thin permalloy films with long axis ranging between several microns to several millimeters, provided that the ratio of the film long and short axes is large enough. We also show that the thin film elliptical structures exhibit a wide range of effective anisotropy fields, from less than 10 Oe up to more than 100 Oe. We discuss the advantage of shape anisotropy in the fabrication of planar Hall effect sensors with high field resolution.