We have used time resolved scanning Kerr microscopy to image collective spin wave modes within a 2D array of magnetic nanoelements. Long wavelength spin waves are confined within the array as if it was a continuous element of the same size but with effective material properties determined by the structure of the array and its constituent nanoelements. The array is an example of a magnonic metamaterial, the demonstration of which provides new opportunities within the emerging field of magnonics.

Low temperature oxidation mechanisms of nanocrystalline magnetite thin film J. Appl. Phys. 113, 013510 (2013) In situ control of electronic phase separation in La1/8 Pr4/8Ca3/8MnO3/PNM-PT thin films using ferroelectricpoling-induced strain J. Appl. Phys. 113, 013705 (2013) Spin precession modulation in a magnetic bilayer Appl. Phys. Lett. 101, 262406 (2012) Alternating domains with uniaxial and biaxial magnetic anisotropy in epitaxial Fe films on BaTiO3 Appl. Phys. Lett. 101, 262405 (2012) Additional information on J. Appl. Phys. We have studied the evolution of the magnetic in-plane anisotropy in epitaxial Fe/GaAs films of both ͑001͒ and ͑110͒ orientation as a function of the Fe layer thickness using the longitudinal magneto-optic Kerr effect and Brillouin light scattering. Magnetization curves which are recorded in situ during film growth reveal a continuous change of the net anisotropy axes with increasing film thickness. This behavior can be understood to arise from the combination of a uniaxial and a cubic in-plane magnetic anisotropy which are both thickness dependent. Structural analysis of the substrate and Fe film surfaces provides insight into the contribution of atomic steps at the interfaces to the magnetic anisotropy. Changing the degree of crystalline order at the Fe-GaAs interface allows us to conclude that the magnetic anisotropies are determined by atomic scale order.

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All-optical pump-probe measurements of magnetization dynamics have been performed upon epitaxial Co 2 MnSi͑001͒ Heusler alloy thin films annealed at temperatures of 300, 400, and 450°C. An ultrafast laserinduced modification of the magnetocrystalline anisotropy triggers precession which is detected by timeresolved magneto-optical Kerr effect measurements. From the damped oscillatory Kerr rotation, the frequency and relaxation rate of the precession is determined. Using a macrospin solution of the Landau-Lifshitz-Gilbert equation the effective fields acting upon the sample magnetization are deduced. This reveals that the magnetization is virtually independent of the annealing temperature while the fourfold magnetocrystalline anisotropy decreases dramatically with increasing annealing temperature as the film structure changes between the B2 and L2 1 phases. From the measured relaxation rates, the value of the apparent Gilbert damping parameter is found to depend strongly upon the static field strength and in-plane static field orientation. The variation of the apparent damping parameter is generally well reproduced by an inhomogeneous broadening model in which the presence of B2 and L2 1 phases leads to a large dispersion of the magnetocrystalline anisotropy. However, for the sample annealed at a temperature of 300°C, the lack of a detailed fit to the data suggests that the apparent anisotropy of the apparent damping parameter might alternatively arise due to a network of dislocations with fourfold symmetry.