AVS 45th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Thursday Sessions
       Session MI-ThP

Paper MI-ThP7
Nonlinear Magneto-Optical Kerr Effect in Co-Cu Nanogranular Films

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Magnetic Interfaces and Nanostructures Poster Session
Presenter: T.V. Misuryaev, Moscow State University, Russia
Authors: T.V. Misuryaev, Moscow State University, Russia
E.A. Ganshina, Moscow State University, Russia
S.V. Guschin, Moscow State University, Russia
T.V. Murzina, Moscow State University, Russia
O.A. Aktsipetrov, Moscow State University, Russia
Correspondent: Click to Email
Magnetic nanostructures and surfaces of magnetic materials have attracted a lot of attention recently because of the observation of new magnetic effects which are not observed in the bulk materials. Apart from magnetic phenomena such as giant magnetoresistance and oscillatory coupling through nonmagnetic spacers magnetic nanostructures can reveal significant nonlinear-optical effects induced by magnetization, e.g. the giant nonlinear magneto-optical Kerr effect (NOMOKE). Magnetization induced optical second harmonic generation (MSHG) has been demonstrated to be effective, sensitive and versatile probe of macroscopic magnetic properties of surfaces and buried interfaces. In this paper both magneto-optical Kerr effect (MOKE) and NOMOKE are studied in granular films composed by nanocrystals of Co in Cu matrix. The samples of Co-Cu granular films were prepared by the co-deposition of Co and Cu on fused quartz substrate. The films thickness is about 200 nm. The mean size of Co nanocrystals is about 60 nm for the Co@sub 0.42@Cu@sub 0.58@ film measured by STM technique. The output of a Q-switched YAG:Nd@super +3@ laser at 1064 nm, with a pulse duration of 15 ns and an intensity of 2 MW/cm@super 2@ is used for the MSHG studies. MOKE spectra for Co@sub 0.42@Cu@sub 0.58@ film are measured in the energy range of 1.2-3.6 eV. The azimuthal anisotropy of the SHG intensity observed can be attributed to the existence of a polar axis in the structure of the Co-Cu granular films, which gives rise to a bulk electrodipole susceptibility. This polar structure can be caused by a predominant regular asymmetry of the filmvacuum interface during film processing. MSHG is studied in the polar, longitudinal and transversal NOMOKE configurations. The magneto-induced rotation the second harmonic (SH) wave polarization, the magneto-induced shift of the SH wave phase (the MSHG interferometry) and magneto-induced changes in the SHG intensity are measured. For all configurations, the NOMOKE parameters exceed the MOKE parameters at least by an order of magnitude. The interference in the far-field region of the SH fields generated by the interface and bulk nonmagnetic and magneto-induced contributions to the nonlinear polarization is suggested as a mechanism of the NOMOKE enhancement.