Dependence of the pole-tip remanence on the medium magnetization state underneath the trailing shield of a perpendicular write head

Understanding the physical mechanisms responsible for the write head pole-tip remanence is critical for making perpendicular recording a practically viable technology. In this paper, one of these mechanisms is explored in detail by using a contact scanning recording tester. The pole-tip remanence of unlaminated perpendicular write heads is studied by varying the magnetization states underneath the trailing shield. It is found that the net medium magnetization underneath the trailing shield acts effectively as magnetomotive force in the head-soft underlayer magnetic flux circuit. A clear correlation between the pole-tip remanence and the medium magnetization state is' demonstrated and characterized. The medium magnetization facilitates the head remanence effectively, resulting in significant erasure after write. The stiffness of the remanence shows a clear dependence on the current amplitude of the prior writing. The large physical dimension of the trailing shield makes the effect of medium magnetization significantly nonlocal. (c) 2005 American Institute of Physics.