Novel Permanent Magnets and Their Uses

Abstract

Two changes have gone hand in hand during the 20^th century. First, applications were conceived that required new or greatly improved materials. Need being the mother of invention, materials were then developed to satisfy the application needs. Permanent magnets are today used in devices that could only have been dreamed about 25 years ago. Who could have foreseen, for example, the advances in data storage that have occurred over the last 15 years? Hard disk drives of under 10 megabytes in size and with random access times of over 65 milliseconds were the norm in 1984. Today, the standard drive is over 8 gigabytes, is smaller in size and costs less than a fourth of the old drives, with an access time of 10 milliseconds and more than 33 mbps burst throughput. Novel has two interpretations: first it may refer to the magnetic material or it may refer to the application of a material. Several examples of each are presented.