Kazuhiro Momata

Magnetoresistive thin‐film sensor with permanent magnet biasing film

Magnetic characteristics have been investigated for a magnetoresistive thin‐film sensor biased using a permanent magnet thin film. Here, Co‐Pt thin film is applied to the device as a bias film. Such microlithographed Co‐Pt thin films show the same magnetic properties as as‐sputtered films. Biasing strength depends on the permanent magnet film thickness, its composition or magnetic properties, and the biasing angle. The output of the sensor is very high.

Soft magnetic properties of NiFeRu thin films and their application to biasing films in magnetoresistive elements

Abstract The effects of the addition of Ru on the magnetic properties of permalloy thin films have been investigated. The alloy composition was (Ni81Fe19)1−xRux; the films were sputtered onto glass substrates at temperatures between room temperature and 200°C. The saturation magnetization, coercivity, and anisotropy field decrease with increasing Ru content. The electrical resistivity initially increases rapidly with increasing Ru content, then saturates at approximately 6% Ru, at a value of approximately 90 × 10 −8 Ω m . Although the magnetoresistance change ( Δϱ ϱ ) does not decrease, the magnetoresistivity ( Δϱ ϱ ) decreases with increasing Ru content due to increased resistivity (ϱ). The magnetostriction moves from minus to plus with increasing Ru content and reaches nearly zero at 6% Ru. Fabricated magnetoresistive heads with the (NiFe)Ru/Ta/NiFe structure show high output and noiseless wave forms.