Large Coercive Field of 45 kOe in a Magnetic Film Based on Metal-Substituted ε-Iron Oxide.

Magnetic ferrites are stable, sustainable, and economical. Consequently, they have been used in various fields. The development of large coercive field (large Hc) magnetic ferrites is a very important but challenging issue to accelerate the spread of use and to expand practical applications. In this study, we prepared a rhodium-substituted ε-iron oxide film and observed a remarkably large Hc value of 35 kOe at room temperature. This is the largest value among magnetic ferrites to date. Such a large-Hc ferrite is expected to greatly expand the application of magnetic ferrites. Furthermore, when the temperature dependence of the magnetic properties was measured, an even larger Hc value of 45 kOe was recorded at 200 K. Such large Hc values are much larger than those of conventional hard magnetic ferrites.