Acoustic Plasmons in Nickel and Its Modification upon Hydrogen Uptake

In this work, we study, in the framework of the ab initio linear-response time-dependent density functional theory, the low-energy collective electronic excitations with characteristic sound-like dispersion, called acoustic plasmons, in bulk ferromagnetic nickel. Since the respective spatial oscillations in slow and fast charge systems involve states with different spins, excitation of such plasmons in nickel should result in the spatial variations in the spin structure as well. We extend our study to NiHx with different hydrogen concentrations x. We vary the hydrogen concentration and trace variations in the acoustic plasmons properties. Finally, at x=1 the acoustic modes disappear in paramagnetic NiH. The explanation of such evolution is based on the changes in the population of different energy bands with hydrogen content variation.

Automated summary

In this work, we investigate the low-energy collective electronic excitations with sound-like dispersion, called acoustic plasmons, in ferromagnetic nickel using ab initio linear-response time-dependent density functional theory. The excitation of these plasmons results in spatial variations in the spin structure in nickel. We further study the variations in the acoustic plasmons properties in NiHx with different hydrogen concentrations.