| 摘要 |
PURPOSE:To obtain a sharp and large pulse voltage by laminating a magnetic thin film having small coercive force and then a magnetic thin film having large coercive force on a substrate whose coefficient of thermal expansion is close to those of the magnetic thin film, and providing a pickup coil. CONSTITUTION:On a glass substrate having, for example, thermal expansion 100X10<-7>/ deg.C, coefficient of a magnetic alloy thin film (having a 105X10<-7>/ deg.C) of 42wt% Ni, 28wt% Fe and 30wt% Co is vacuum-deposited to 3,800Angstrom thickness. Then, another film of alloy of 17.5wt% Ni, 525wt% Fe and 30wt% Co (said coefficient of 115X10<-7>/ deg.C) with greater coercive force than that of the former is laminated to 3,200Angstrom . In this case, making the coefficient of thermal expansion of the layer of the small coercive force coincide within +20--50% with that of the substrate, the coefficient of thermal expansion of the layer of the large coercive force is made coincide in the same way. Thus, a sensor which generates a large pulse voltage with high steepness across a pickup coil without depending upon the intensity of an external magnetic field and a change in direction is obtained. |
