Magnetic-force-sensing STM: novel application of STM for simultaneous measurement of topography and field gradient of magnetic recording heads

Abstract

We present a technique for simultaneously measuring the topography and the field gradient of recording heads using a scanning tunneling microscope with a cantilever-shaped magnetic tip. The field from the recording head excited by an alternating current vibrates the tip of the STM, and this causes modulation in tunneling current. This modulated signal is detected by a lock-in amplifier and is processed to obtain a magnetic-force image. The low-frequency components of the tunneling current represent the topography of the air-bearing surface of the recording head in a normal STM mode. The effects of the head current and the tunneling voltage upon the field gradient were also investigated. © 1992.