Anisotropy of magnetization-induced surface optical second harmonic generation from Co doped rutile TiO2

We have investigated the surface magnetization anisotropy of 5 at% Co doped rutile TiO2 (1 1 0) using magnetization-induced optical second harmonic generation (MSHG) in the longitudinal Kerr configuration with an incident beam angle of 4°. The MSH intensity pattern from the Co:TiO2 without surface Co clusters showed two anisotropic lobes at the second harmonic photon energy of image. Since MSH intensity is proportional to surface magnetization, the result indicates an anisotropy of the surface magnetization of Co:rutile TiO2 (1 1 0). This confirms the possibility that 5 at% Co:rutile TiO2 (1 1 0) is a ferromagnetic dilute magnetic semiconductor at its surface, as proposed in our previous paper.