The spectroscopic splitting factor g and the Gilbert damping constant G are magnetic parameters accessible to ferromagnetic resonance (FMR) measurements, which apart from the magneto-crystalline anisotropy energy can provide information on the spin-orbit coupling in magnetically ordered material. Whereas the effect of spin-orbit coupling has been thoroughly investigated and is well understood in insulating transition metal compounds, in 3d-metallic magnetic compounds the microscopic mechanism still needs further clarification. Particularly in thin films and multilayers interface effects and interaction between layers can modify both spin and orbital moments leading to changes of the g-value and the Gilbert damping constant. Experimental results are presented from frequency dependent FMR measurements on Co epitaxial films grown on Cr(001) and on films of the alloy Co 1−x Fe x (100) deposited on MgO(001), and from recent studies on Fe(100) films grown on InAs(001). The experimental data yield clear evidence of the importance of surfaces or interfaces of the films on the magnitude of orbital and spin moment.
An inverse solution of the two-layer thermal wave problem has been derived, which allows us to determine the relevant thermal transport parameters, the thermal diffusion time and the thermal reflection coefficient, respectively, the ratio of the effusivities of the two layers, deduced from the relative minimum or maximum of the calibrated phase lags measured between the periodically modulated excitation of the thermal wave and the detected thermal response. Applying a functional transformation by multiplying the calibrated phase lags with the variable (1∕f1∕2)q, where f is the modulation frequency of excitation and q a positive or negative real number close to zero, the inversion method is extended to other values of the calibrated phase lags measured in the neighborhood of the phase minimum or maximum. The application potential of these two solution methods is studied by analyzing the phase lags measured as a function of frequency for two-layer systems of technological importance, e.g., different plasma-deposited hard coatings on tool steel, coated cutting tools after friction wear, and a sample of a shape memory alloy (NiTi) after mechanical surface treatment.
We report thermopower measurements for the nickel titanium shape memory alloy Ni0.507Ti0.493. Our measurements reveal abrupt changes in the temperature dependence of thermopower, which correlate well with the structural phase transition between the austenitic and martensitic phases. These transition effects in thermopower are more clearly defined than in the resistivity, which is also reported. In the martensitic phase, thermopower exhibits standard metallic diffusion behavior with a nonlinearity, which is consistent with either a small peak in the density of states just below the Fermi level, as calculated by Kulkova, Egorushkin, and Kalchikhin [Solid State Commun. 77, 667 (1991)], or else electron–phonon mass enhancement. For thermally or mechanically treated samples, the magnitude of the transition effects in thermopower are reduced.
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