Search

We review our theoretical studies of the spin dynamics of ultrathin ferromagnetic films adsorbed on metallic substrates. Of interest are the spin waves with wave vector from the center of the Brillouin zone to its boundary. We utilize a realistic electronic structure for the substrate/adsorbate combination through an empirical tight binding description of the electronic structure of the materials involved, and the spin excitations are explored through the Random Phase Approximation. We can examine very large systems with this scheme, such as multilayer films placed on fully semi-infinite substrates. One principal finding is the adiabatic approximation breaks down qualitatively for these systems. We illustrate for Co films on Cu(100) where we also find excellent agreement with experiment. We conclude by discussing recent data for the Fe bilayer on W(110) where, after an excellent account of the measured exchange stiffness, we find the large wave vector spin waves generated by theory to be far too stiff. Index Terms--SPEELS, spin waves, ultrathin ferromagnets.

Macro-spin simulations have been performed to study the synchronization of pairs of serially connected spin torque oscillators in parallel with a capacitor. The sensitivity to the STO process variation, which is modeled by the anisotropy field distribution for different STO samples, can be dramatically decreased by the coupling of a capacitor in the circuit. There exists an optimum capacitance where the multi-STO synchronized state develops the highest robustness. Index Terms--Preferred phase shift, spin torque oscillator, synchronization.