arXiv subjects

V. Shalagatskyi

Publications and source records attributed to V. Shalagatskyi.

3 recordsLinked to original sources

arXiv2017

Ultrafast electron-phonon-magnon interactions at noble metal-ferromagnet interfaces

Ultrafast optical excitation of gold-cobalt bilayers triggers the nontrivial interplay between the electronic, acoustic, and magnetic degrees of freedom. Laser-heated electrons generated at the gold-air interface diffuse through the layer of gold and strongly overheat the lattice in cobalt resulting in the emission of ultrashort acoustic pulses and generation of exchange-coupled magnons. Time-resolved optical measurements allow for extracting the thermal boundary (Kapitza) resistances at metal/metal interfaces and the hot electron diffusion length in ferromagnetic materials. Both the experimental data and the analytical treatment of the two-temperature model reveal the role of the Kapitza resistance in transient lattice overheating.

cond-mat.mtrl-sci↗

arXiv2016

Ultrafast Magnetoelastic Probing of Surface Acoustic Transients

We generate in-plane magnetoelastic waves in nickel films using the all-optical transient grating technique. When performed on amorphous glass substrates, two dominant magnetoelastic excitations can be resonantly driven by the underlying elastic distortions, the Rayleigh Surface Acoustic Wave and the Surface Skimming Longitudinal Wave. An applied field, oriented in the sample plane, selectively tunes the coupling between magnetic precession and one of the elastic waves, thus demonstrating selective excitation of coexisting, large amplitude magnetoelastic waves. Analytical calculations based on the Green's function approach corroborate the generation of the non-equilibrium surface acoustic transients.

cond-mat.mtrl-sci↗

arXiv2013

Detection of shorter-than-skin-depth acoustic pulses in a metal film via transient reflectivity

The detection of ultrashort laser-generated acoustic pulses at a metal surface and the reconstruction of the acoustic strain profile are investigated. A 2 ps-long acoustic pulse generated in an SrRuO$_{3}$ layer propagates through an adjacent gold layer and is detected at its surface by a reflected probe pulse. We show that the intricate shape of the transient reflectivity waveform and the ability to resolve acoustic pulses shorter than the optical skin depth are controlled by a single parameter, which is determined by the ratio of the real and imaginary parts of the photoelastic constant of the material. We also demonstrate a Fourier transform-based algorithm that can be used to extract acoustic strain profiles from transient reflectivity measurements.

cond-mat.mtrl-sci↗