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Inductive measurement of ultrafast magnetization dynamics in thin-film Permalloy
An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are…
Ferromagnetic resonance linewidth in metallic thin films: Comparison of measurement methods
Stripline (SL), vector network analyzer (VNA), and pulsed inductive microwave magnetometer (PIMM) techniques were used to measure the ferromagnetic resonance (FMR) linewidth for a series of Permalloy…
Frequency modulation of spin-transfer oscillators
Spin-polarized dc electric current flowing into a magnetic layer can induce precession of the magnetization at a frequency that depends on current. We show that addition of an ac current to this dc…
Direct-current induced dynamics in Co90 Fe10/Ni80 Fe20 point contacts.
This work directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current, resulting in a microwave oscillator that can be tuned from below 5 to above 40 GHz.
Linear relation between Heisenberg exchange and interfacial Dzyaloshinskii–Moriya interaction in metal films
The Dzyaloshinskii–Moriya exchange induces a range of chiral phenomena in spintronic systems. Experiments now confirm that this interaction is proportional to the Heisenberg exchange, reflecting…
Current-driven microwave dynamics in magnetic point contacts as a function of applied field angle
We have measured microwave frequency, current-driven magnetization dynamics in point contacts made to spin valves as a function of applied field strength and angle relative to the film plane. As the…
Mutual phase-locking of microwave spin torque nano-oscillators
It is shown that two STNOs in close proximity mutually phase-lock—that is, they synchronize, which is a general tendency of interacting nonlinear oscillator systems.
Ultra-low magnetic damping of a metallic ferromagnet
Materials with low magnetic damping are important for a range of applications but are typically insulating, which limits their use. Thanks to a unique feature of the band structure, similar levels of…
Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current.
- D. Rudolf, C. La-o-vorakiat, P. Oppeneer
- Physics, Materials ScienceNature communications
- 4 September 2012
Spatially separate the spin dynamics using Ni/Ru/Fe magnetic trilayers and surprisingly find that optically induced demagnetization of the Ni layer transiently enhances the magnetizations of the Fe layer when the two layer magnetizations are initially aligned parallel.
Probing the timescale of the exchange interaction in a ferromagnetic alloy
- S. Mathias, C. La-o-vorakiat, H. Kapteyn
- Materials Science, PhysicsProceedings of the National Academy of Sciences
- 27 February 2012
This work uses extreme ultraviolet pulses from high-harmonic generation as an element-specific probe of ultrafast, optically driven, demagnetization in a ferromagnetic Fe-Ni alloy (permalloy), and shows that for times shorter than the characteristic timescale for exchange coupling, the magnetization of Fe quenches more strongly than that of Ni.