A rotor element configured for movement relative to a stator includes a backing member formed, at least in part, from a ferromagnetic material; a first magnetic pole having a first polarity; and a second magnetic pole having a second polarity, opposite the first polarity. The first magnetic pole and the second magnetic pole are coupled to a first surface of the backing member such that the second magnetic pole is disposed, relative to the first magnetic pole, at a distance defined in a direction of a width of the backing member. A thickness of the backing member is varied along the width of the backing member to form a plurality of alternating first portions and second portions. The first portions include protrusions extending from a second surface of the backing member, opposite the first surface, such that the first portions are thicker than the second portions.