New Applications

Although it was discovered more than 100 years ago that the electrical resistance of certain metals can be influenced by an applied magnetic field, it is only in recent years that proposals have been put forward for practical applications of this "magnetoresistance effect," as it is called. There are two important reasons for the revival of research in this field. The first is the development of magnetic recording in the direction of increasingly high information densities, which calls for magnetic sensors of a compactness that cannot be achieved with conventional inductive sensors. The second is the development of methods, related to integrated circuit technology, by which micropatterns can be made in thin metal layers, making it possible to fabricate tiny magnetoresistive elements capable of detecting magnetic fields varying on a micron scale.