Ferromagnetic multilayer film, magnetoresistance effect element, and method for manufacturing ferromagnetic multilayer film

A ferromagnetic multilayer film comprising:

• a first ferromagnetic layer;
• a first interposed layer stacked on the first ferromagnetic layer;
• a second interposed layer stacked on the first interposed layer;
• a magnetic coupling layer stacked on the second interposed layer;
• and
• a second ferromagnetic layer stacked on the magnetic coupling layer,
• wherein the first ferromagnetic layer and the second ferromagnetic layer are magnetically coupled by exchange coupling via the first interposed layer, the second interposed layer, and the magnetic coupling layer such that magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are antiparallel to each other,
• a main element of the magnetic coupling layer is Ru, Rh, or Ir,
• a main element of the first interposed layer is the same as the main element of the magnetic coupling layer,
• a main element of the second interposed layer is different from the main element of the magnetic coupling layer,
• a thickness of the first interposed layer is greater than or equal to 1.5 times and less than or equal to 3.2 times an atomic radius of the main element of the first interposed layer, and
• a thickness of the second interposed layer is less than or equal to 1.5 times an atomic radius of the main element of the second interposed layer.