A lock is provided with a housing, a shackle movably coupled to the housing, and a locking arrangement movable between a locked state and an unlocked state. One embodiment provides for etching a series of interlocking geometric trenches into a device layer and filling the trenches with a non-conductive dielectric material. Since a part of a magnetic flux emitted from the exposed surface to the outside flows in the exposed surface while being spread a little in the width direction, spread of the magnetic flux is suppressed at the time of recording.