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 2ℏω=3.13eV. 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.