As the material for a permanent magnet formed of an oxide, there is known hexagonal system M type (magnetoplumbite type) Sr ferrite or Ba ferrite. The ferrite magnetic materials made of the ferrites are made available as permanent magnets in the form of ferrite sintered bodies or bonded magnets. In recent years, with miniaturization and enhancement of performances of electronic components, permanent magnets made of ferrite magnetic materials have also been required to have high magnetic characteristics while being small-sized.
As the indexes of the magnetic characteristics of a permanent magnet, generally, the residual magnetic flux density (Br) and the coercive force (HcJ) are used. Those which are high in these are evaluated as having high magnetic characteristics. Conventionally, from the viewpoint of improving the Br and the HcJ of the permanent magnet, a study has been done by the changing of the composition such as the inclusion of a prescribed element in a ferrite magnetic material.
For example, in the following Patent Document 1, there is shown oxide magnetic materials capable of providing a ferrite sintered magnet having high Br and HcJ by allowing M type Ca ferrite to include at least La, Ba, and Co.
Further, in the following Patent Document 2, there are disclosed oxide magnetic materials capable of providing ferrite sintered magnets having high Br and HcJ by allowing M type Ca ferrite to include La, Sr, and Co. Further, in the following Patent Document 3, there are disclosed sintered magnets having high Br and HcJ by allowing M type Sr ferrite to include Sr, La, and Co.