Magnetic device and manufacturing method of magnetic device

A magnetic device comprising a magnetoresistive effect element, the magnetoresistive effect element including:

• a first ferromagnet;
• a conductor;
• an oxide provided between the first ferromagnet and the conductor, the oxide including a first oxide of a rare-earth element and a second oxide of an element of which a covalent radius is smaller than a covalent radius of the rare-earth element;
• a second ferromagnet;
• and
• a seed material provided between the first ferromagnet and the second ferromagnet,
• wherein the first ferromagnet is sandwiched between the seed material and the oxide.