High-resolution, tunneling-stabilized magnetic imaging and recording

Abstract

We have used a scanning tunneling microscope (STM) to record and image magnetic regions on the surface of a hard disk. The usual rigid STM tip was replaced by a compliant magnetized Fe film tip. As a result, tunneling images were combinations of the surface topography and variations in the magnetic force between the Fe film tip and the disk surface. We believe that the recording process relied on maintaining the proximity of the magnetized Fe film tip near the disk surface. Apparently, the magnetic field was focused near the Fe film tip with sufficient intensity to change the surface magnetization of the disk. We have recorded spots on the disk within a 500 nm×500 nm area. These spots were subsequently imaged with the same STM tip. Our best magnetic image resolution was 20 nm. The compliance of the Fe film tips was such that image contrast due to variation of the magnetic force on the tip corresponded to z motions of the piezoelectric translator as large as 50 nm.