arXiv subjects

Mikhail Kostylev

Publications and source records attributed to Mikhail Kostylev.

40 records · Page 3Linked to original sources

arXiv2012

Asymmetry of modal profiles of dipole-exchange spin waves in thin high-magnetic moment metallic ferromagnetic films

The asymmetry of the modal profiles for dipole-exchange spin waves propagating in in-plane magnetized ferromagnetic films at a right angle to the applied magnetic field has been investigated theoretically. It was found that in the large-magnetic moment ferromagnetic metallic films with typical thicknesses 10-60 nm the fundamental mode of the spectrum is localized at the surface opposite to the surface of localization of the exchange-free Damon-Eshbach surface wave. This anomalous localization of the wave does not affect the non-reciprocity of spin wave excitation by microstrip and coplanar transducers but may be detected in other types of experiments.

cond-mat.mes-hall↗

arXiv2010

Exchange anisotropy pinning of a standing spin wave mode

Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin wave thickness mode in Ni(80)Fe(20)/Ir(25)Mn(75) exchange biased bilayers was studied for a range of IrMn thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique `fingerprint' of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet/antiferromagnet interface anisotropy. Thermal effects are studied for ultra-thin antiferromagnetic Ir(25)Mn(75) thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

cond-mat.mtrl-sci↗

arXiv2010

Effect of disorder studied with ferromagnetic resonance for arrays of tangentially magnetized sub-micron Permalloy discs fabricated by nanosphere lithography

Tangentially magnetized trigonal arrays of sub-micron Permalloy discs are characterized with ferromagnetic resonance to determine the possible contributions to frequency and linewidth from array disorder. Each array is fabricated by a water-surface self-assembly lithographic technique, and consists of a large trigonal array of 700 nm diameter magnetic discs. Each array is characterized by a different degree of ordering. Two modes are present in the ferromagnetic resonance spectra: a large amplitude, `fundamental' mode and a lower amplitude mode at higher field. Angular dependence of the resonance field in a very well ordered array is found to be negligible for both modes. The relationship between resonance frequency and applied magnetic field is found to be uncorrelated with array disorder. Linewidth is found to increase with increasing array disorder.

cond-mat.mes-hall↗

arXiv2007

Nonlinear mode conversion in monodomain magnetic squares

Modifications of spatial distributions of dynamic magnetization corresponding to spinwave eigenmodes of magnetic squares subjected to a strong microwave excitation field have been studied experimentally and theoretically. We show that an increase of the excitation power leads to a nonlinear generation of long-wavelength spatial harmonics caused by the nonlinear cross coupling between the eigenmodes. The analysis of the experimental data shows that this process is mainly governed by the action of the nonlinear spin-wave damping. This conclusion is further supported by the numerical calculations based on the complex Ginzburg-Landau equation phenomenologically taking into account the nonlinear damping.

nlin.PS↗