Spin torque ferromagnetic resonance with magnetic field modulation

We demonstrate a technique of broadband spin torque ferromagnetic resonance (ST-FMR) with magnetic field modulation for measurements of spin wave properties in magnetic nanostructures. This technique gives great improvement in sensitivity over the conventional ST-FMR measurements, and application of this technique to nanoscale magnetic tunnel junctions (MTJs) reveals a rich spectrum of standing spin wave eigenmodes. Comparison of the ST-FMR measurements with micromagnetic simulations of the spin wave spectrum allows us to explain the character of low-frequency magnetic excitations in nanoscale MTJs.Comment: Also see: http://faculty.sites.uci.edu/krivorotovgroup

Low relaxation rate in a low-Z alloy of iron

The longest relaxation time and sharpest frequency content in ferromagnetic precession is determined by the intrinsic (Gilbert) relaxation rate \emph{$G$}. For many years, pure iron (Fe) has had the lowest known value of $G=\textrm{57 Mhz}$ for all pure ferromagnetic metals or binary alloys. We show that an epitaxial iron alloy with vanadium (V) possesses values of $G$ which are significantly reduced, to 35$\pm$5 Mhz at 27% V. The result can be understood as the role of spin-orbit coupling in generating relaxation, reduced through the atomic number $Z$.Comment: 14 pages, 4 figure

Radiation Heating of Primary Collimators at Ramping

A time-dependent temperature map is derived for the primary jaw of the momentum collimation system during the high transient loss period which is to occur at the beginning of the ramp of acceleration. An adequate margin factor is obtained for a loss of 5% of the nominal stored beam and for the nominal parabolic ramping curve

THE STUDY OF THE STRUCTURE AND PROPERTIES OF HARD ALLOY КNТ16 DURING ION NITRIDING

В качестве объектов исследования использовались образцы из твердого сплава марки КНТ16. В ходе исследования было проведено ионное азотирование твёрдого сплава, испытания резанием, испытание на изгиб, рентгеноструктурный анализ, электронная микроскопия.As object of research used samples of solid alloy grade КNТ16. The study was carried out ion nitriding, hard alloy, cutting, bending test, x-ray structural analysis, electron microscopy

Magnetic phase transitions in Ta/CoFeB/MgO multilayers

We study thin films and magnetic tunnel junction nanopillars based on Ta/Co$_{20}$Fe$_{60}$B$_{20}$/MgO multilayers by electrical transport and magnetometry measurements. These measurements suggest that an ultrathin magnetic oxide layer forms at the Co$_{20}$Fe$_{60}$B$_{20}$/MgO interface. At approximately 160 K, the oxide undergoes a phase transition from an insulating antiferromagnet at low temperatures to a conductive weak ferromagnet at high temperatures. This interfacial magnetic oxide is expected to have significant impact on the magnetic properties of CoFeB-based multilayers used in spin torque memories