Enhanced broadband microwave reflection loss of carbon nanotube ensheathed Ni–Zn–Co-ferrite magnetic nanoparticles

• Carbon nanotube ensheathed Ni–Zn–Co-ferrite magnetic nanoparticles were prepared.
• Sufficiently high magnetization was retained after nanocomposite formation.
• Enhanced microwave absorption occurs by nanocomposite.
• Consolidated theoretical explanation for high microwave absorption is proposed.

Ni–Zn–Co-ferrite (NZCoF) nanoparticles prepared by sol–gel method were ensheathed in multi-walled carbon nanotubes (MWCNT) to form the desired composite NZCoF–CNT. Magnetization curves of samples indicate presence of mixed state of superparamagnetism and ferrimagnetism, with the composite indicating significant retention of magnetic behavior of NZCoF despite presence of non-magnetic MWCNT. Microwave frequency reflection loss of the samples was measured, and absorption is evidently enhanced in NZCoF–CNT, compared to that of NZCoF. A consolidated theoretical explanation has been proposed explaining enhanced microwave absorption in present and similar previous works.