Interlayer coupling in spin valves studied by broadband ferromagnetic resonance

Abstract

Magnetization dynamic response of coupled and uncoupled spin valves with structure NiFe(20nm)/Cu(tCu)/NiFe(20nm)/IrMn(10nm) is probed using broadband ferromagnetic resonance absorption measurements. The coupling intensity between the free and pinned layers is tailored by varying the Cu thickness tCu. Broadband spectra exhibit two resonant modes for each value of applied field. It is observed that the coupling among NiFe layers modifies the amplitude of the absorption peaks and also the shape of the dispersion relations for each mode, which becomes particularly distorted at the anti-parallel magnetization state. The observed phenomena is well described by applying a semianalytical model that properly takes into account the coupling interactions and allows an efficient numerical calculation of the absorption peak amplitudes, and the dispersion relation shapes.

Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings

“…Microwaves with longitudinal and transverse polarizations with respect to an external magnetic field then excite A and O resonance modes, respectively. 31,[42][43][44][45][46] We develop the theory for magnetization dynamics and damping based on the Landau-Lifshitz-Gilbert equation with mutual pumping of spin currents and spin transfer torques based on the spin diffusion model with quantum mechanical boundary conditions. 27,47,48 We confirm 28,49 that the additional damping of O modes is larger than that of the A modes.…”

Annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films

“…Detailed information on the experimental setup and procedure used to the obtain the absorbed microwave power is found in Ref. 5.…”

Symmetry effects on the static and dynamic properties of coupled magnetic oscillators

“…Recently, the implications of symmetry and symmetrybreaking on the solutions of the LLG equation have been explored via a theoretical description of magnon-magnon anti-crossings in anti-ferromagnetically coupled oscillators. In all these works the breaking of symmetry, either externally by applying a magnetic field or internally by tuning the material composition, was identified as key in preventing two modes' crossing [4][5][6][7][8][9]. In these reports, the results are analysed mathematically by looking at the commutation of various transformation matrices and the resulting conserved quantities.…”