Sub-Nano Tesla Resolution Differential Magnetic Field Sensor Utilizing Asymmetrical Magnetoimpedance in Multilayer Films

Abstract

Asymmetrical magnetoimpedance (AMI) in multilayer thin films with cross anisotropy has been used for the development of a low noise, sensitive and quick response miniature magnetic sensor. The sensor is driven by a sinusoidal current of 90 MHz biased with a dc current. For an AMI film element of dimensions 5 mm long, 40 /spl mu/m wide, and having an anisotropy angle of 45/spl deg/, the field detection resolution is in the order of 1 /spl mu/ Oe for both ac and dc fields of magnitude 1 Oe. The maximum response speed is in the order of 1 MHz.