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 H c ) 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 H c value of 35 kOe at room temperature. This is the largest value among magnetic ferrites to date. Such a large- H c 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 H c value of 45 kOe was recorded at 200 K. Such large H c values are much larger than those of conventional hard magnetic ferrites.