Ultrahigh vacuum angle-dependent Faraday effect experiment on ultrathin magneto-optical materials

Determination of magnetic anisotropy on perpendicular and longitudinal fields in most magneto-optical materials is usually essential in magnetic measurements. However, 3D information is still insufficient and may be misled due to only two spin vectors. The vacuum magneto-optical Faraday effect measurement (the transmission mode of magneto-optics technique) in an ultrahigh vacuum system, a new concept for the reconstruction of 3D magnetic anisotropy is introduced. The Faraday rotation in the ultrathin (magnetic film)/(optical crystal) system exhibits a polar plane oscillation as a function of incidence angle. The crystal birefringence is responsible for causing the oscillation. The Faraday rotation, which consists of crystal optics and magneto-optics, originates from the crystal and the ultrathin film, respectively. Alternatively, we clarify a debate that the easy axis of the Co/ZnO(0001) film is only located at the plane. Through the observation of the angle-dependent coercivity, the magnetic easy axis in the proposed multilayer structure including double anisotropy is proposed.