Encapsulation of segmented Pd–Co nanocomposites into vertically aligned carbon nanotubes by plasma-hydrogen-induced demixing

Vertically aligned carbon nanotubes (VA-CNTs) filled with Pd–Co nanocomposites on an Si substrate have been synthesized by microwave plasma-enhanced chemical vapor deposition. It was confirmed that adjacent Pd–Co nanocomposites in the VA-CNTs were compositionally separated. Most CNTs contained Co pillars on top; however, Pd pillars were rarely present. The strong magnetic induction from an individual Co pillar was revealed by electron holography. The simultaneous phenomenon of the demixing by plasma hydrogen irradiation and the preferential encapsulation into CNTs realized the unique Pd–Co nanocomposites.