永久磁石の研究とその問題点

抄録

The main subjects for research of permanent magnets were summarized in this lecture. High coercive force of new permanent magnets are to be expected when fine particle have either high crytsal anisotoropy or anisotoropy of particle shape. In this cases the particle consists of single magnetic domain, and any change of magnetization must occur by domain rotation.
The magnetic energy products of permanent magnets are improved by manufacturing methods such as the formations of columnar grains, the treatements in a magnetic field or the cold working.
Fundamental problem in efficient design of permanent magnets is to know the working of of permanent magnet in various applications. Leakage flux is comparable to effective flux.
It should be determined the leakage factor to design quantatively.
It is essential that the magnetic flux should be stable over long periods of time.
External influences such as external magnetic fields, mechanical shock and magnetic shunt affect the magnetic flux of a permanent magnet. Spontaneous redistributions of domain magnetization may take place without any external influences.