A Study on Thin-Film Magnetic Sensor Using Magneto-Impedance Effect.

Abstract

This paper introduces a magnetic field measurement technique with nano-resolution using a thin-film magnetic sensor. The method consists of a process, where the thin-film magnetic sensor is scanned over the sample, followed by a processing using a deconvolution scheme. In the scanning process, the thin-film magnetic sensor is scanned over the sample perpendicularly to the sensor. The sample is rotated horizontally under the sensor so that data measurements are obtained at different angles and positions. The deconvolution can be performed using existing methods, which are familiar in computed tomography technology. Numerical simulations were performed to demonstrate the technique's capability of achieving nano-resolution measurements of a magnetic field using the thin-film magnetic sensor. Currently, thin-film magnetic sensors are used as reading heads in hard drive disks (HDD), such as thin-film inductive heads, anisotropic magnetoresistive (AMR) heads, and giant magnetoresistive (GMR) heads. Recently, the film thickness of the GMR head, which is most commonly used as the reading head in HDD, is less than 10nm. Previously, the resolution of the measurement was limited by the width of the sensor (ie. 100nm), however, the new technique has the same resolution as the film thickness (ie. 10nm). The measurement techniques of the HDD industry field can be applied to our measurement method.