  A method for growing nanoparticles with different elemental compositions
simply by changing pulsing parameters in a power supply is demonstrated. The
technique is based on high power pulsed hollow cathode sputtering, and the
difference in particle composition ranges from pure Fe and Ni, to fully alloyed
FeNi particles. Several pulses, or bursts, from a hollow cathode are needed in
order to grow a nanoparticle using high power pulses. With this in mind, we
devised a setup with two hollow cathodes of different material, Fe and Ni,
situated in the vicinity of each other. By using two power supplies and a
synchronization unit, the number and size of pulses of each element into the
growth regime of the nanoparticles is controlled, and a tunable mixture of ions
of the two elements is ensured. We here show that the two-target high power
hollow cathode sputtering unit can be a powerful tool for rapid prototyping of
more advanced, customized, nanoparticles, which can be of great importance for
numerous applications.
