Soft magnetic exchange-coupled composite structure, and high-frequency device component, antenna module, and magnetoresistive device including the soft magnetic exchange-coupled composite structure

A soft magnetic exchange-coupled composite structure, comprising:

• a ferrite crystal grain as a main phase, the ferrite crystal grain having a first thin film structure,
• wherein the ferrite crystal grain is oxygen-deficient;
• and
• a soft magnetic metal as an auxiliary phase bonded to the ferrite crystal grain by interfacial bonding on an atomic scale, the soft magnetic metal having a second thin film structure,
• wherein a region of the soft magnetic metal adjacent to an interface with the ferrite crystal grain includes a crystalline soft magnetic metal, and
• the crystalline soft magnetic material has a third thin film structure, the third thin film structure being between the first thin film structure and the second thin film structure.