Nonlinear magnetization-induced terms in garnet film polarization in the second-harmonic generation effect: Theory and experiment (original) (raw)
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Purely magnetization-induced second-harmonic generation in thin garnet films
Transactions of the Magnetics Society of Japan, 2004
Optical second-harmonic generation (SHG) of purely magnetic origin has been observed in thin films of Lu3-x "Bix"Fe5-y Gay O12 grown on (100) oriented gadolinium gallium garnet (GGG) substrates for the purpose of magneto-optical imaging. The films have in-plane magnetization, and when studied in transmission at normal incidence all relevant elements of the crystallographic part of the second order non-linear optical susceptibility tensor vanish identically, while a magnetization-induced contribution remains. The observed rotational anisotropy SHG signal in a transverse magnetic field is demonstrated to be indeed of purely magnetic origin, and can be switched off by applying a polar magnetic field.
Second harmonic generation in anisotropic magnetic films
Physical Review B, 2001
Nonlinear magneto-optical phenomena related to the process of second harmonic generation in anisotropic films of different classes of symmetry are discussed. In the electric-dipole approximation two kinds of nonlinearity of crystallographic and magnetic origin may coexist in noncentrosymmetric crystals. The interference between the corresponding nonlinear optical waves results in novel magneto-optical effects, such as a transversal effect linear in magnetization at normal incidence and a circular magnetic asymmetry with no equivalence between light helicity and magnetization direction change. Epitaxial films of magnetic garnets grown on substrates with different crystallographic orientations were taken as a model anisotropic system for experimental studies. The unambiguous separation of the crystallographic and magnetic contributions to the second harmonic generation is demonstrated with the help of rotational anisotropy experiments. A theoretical model for the nonlinear light propagation in noncentrosymmetric magnetic films is developed. Calculations based on this model are found to be in good agreement with the experimental results.
Magnetization-induced second-and third-harmonic generation in magnetic thin films and nanoparticles
JOSA B, 2005
The results of our recent experimental studies of magnetization-induced second-and third-order nonlinear optical effects in magnetic nanostructures are surveyed. Magnetization-induced variations of the intensity, the polarization state, and the relative phase of the second-harmonic wave are studied in magnetic nanogranular films, self-assembling films with garnet nanoparticles, thin magnetic metal films, and Langmuir-Blodgett films containing rare-earth ions. The nonlinear magneto-optical Kerr effect (NOMOKE) in second-harmonic generation (SHG) from thin magnetic and granular films is shown to exceed the linear magneto-optical Kerr effect by at least 1 order of magnitude. Magnetization-induced optical third-harmonic generation (THG) is observed in thin magnetic metal films and nanogranular films. The NOMOKE in THG from these magnetic nanostructures appears to be of the same order of magnitude as the second-order NOMOKE in SHG. The NOMOKE magnetic contrast in the THG intensity is up to ϳ0.1 in Co x Ag (1Ϫx) nanogranular films. For the THG wave, the magnetization-induced rotation of polarization is up to 10°in thin Fe(110) films, and the relative phase shift is up to 70°in thin Co films. The studies of the magnetization-induced quadratic and cubic nonlinear-optical effects show the interconnection between the magnetic, structural, and magneto-optical properties of magnetic nanomaterials.
Physical Review B, 2004
Magnetization~induced second-harmonic generation (SHG) has been used for the study of thin garnet films. The strong optical absorption of these films at the second harmonic frequency provides a unique possibility to study magnetic and structural properties of the film surface and film/substrate interface separately. When studied in transmission at normal incidence all relevant elements of the crystallographic part of the nonlinear optical susceptibility tensor vanish identically, while a magnetization• induced contribution remains. The purely magnetic origin of SHG from the interface is unambiguously demonstrated. From measurements of the SHG rotational anisotropy and magnetic field dependence, the surface is found to have inclusions which act as nonmagnetic sources of SHG, while the anisotropy causing easy in• plane magnetization is found to be stronger at the interface with the substrate than at the surface of the film.
New Class of High Frequency Nonlinear Magnetic Oscillations in Epitaxial Garnet Films
Le Journal de Physique IV, 1997
We performed magneto-optical investigations of the shape of the magnetization precession trajectory in garnet films at large precession angle. To describe the precession in asymmetric potential well the second order terms of small magnetization deflections are taken into account in the expansion of the thermodynamical potential. It is shown, that zero and second harmonic appear in the magnetization oscillations spectrum. The amplitude of this harmonics are proportional to the square of the exciting field amplitude. The dependence of asymmetric precession degree upon applied field and film parameters is found. The reported effects are like second harmonic generation and light detection effects in nonlinear optics.
Journal of the Optical Society of America B, 2005
Second-harmonic generation (SHG) in magnetically ordered crystals is reviewed. The symmetry of such crystals is determined by the arrangement of both the charges and the spins, so their contributions to the crystallographic and the magnetic structures, respectively, must be distinguished. Magnetic SHG is introduced as a probe for magnetic structures and sublattice interactions. The specific degrees of optical experimentsincluding spectral, spatial, and temporal resolution-lead to the observation of novel physical effects that cannot be revealed by other techniques of probing magnetism. These include local or hidden phase transitions, interacting magnetized and polarized sublattices and domain walls, and magnetic interfaces. SHG in various centrosymmetric and noncentrosymmetric crystal classes of antiferromagnetic oxides such as Cr 2 O 3 , hexagonal RMnO 3 (R ϭ Sc, Y, In, Ho-Lu), magnetic garnet films, CuB 2 O 4 , CoO, and NiO, is discussed.
Applied Physics Letters, 2006
Three-dimensional magnetophotonic crystals ͑MPCs͒ based on artificial opals infiltrated by yttrium iron garnet ͑YIG͒ are fabricated and their structural, optical, and nonlinear optical properties are studied. The formation of the crystalline YIG inside the opal matrix is checked by x-ray analysis. Two templates are used for the infiltration by YIG: bare opals and those covered by a thin platinum film. Optical second-harmonic generation ͑SHG͒ technique is used to study the magnetization-induced nonlinear-optical properties of the composed MPCs. A high nonlinear magneto-optical Kerr effect in the SHG intensity is observed at the edge of the photonic band gap of the MPCs.
Magnetization-induced optical third-harmonic generation in Co and Fe nanostructures
Physical Review B, 2006
Magnetization-induced optical third-harmonic generation (MTHG) is observed in magnetic nanostructures: Co and F e nanolayers and granular films containing Co nanoparticles. Magnetizationinduced variations of the MTHG characteristics in these nanostructures exceed the typical values of linear magneto-optical Kerr effect by at least an order of magnitude: the maximum of magnetic contrast in the MTHG intensity is up to 0.2, the angle of polarization rotation for MTHG is 10 • and the relative phase shift is up to 100 • .