Exchange bias and anisotropy analysis of nano-composite Co84Zr16N thin films

• Exchange bias effect observed in 390 K annealed and field cooled single layer nanocomposite Co84Zr16N (CZN) thin films.
• CZN films are composed of ordered and crystalline ferromagnetic Cobalt nano-clusters embedded in antiferromagnetic matrix.
• Uniaxial magnetic anisotropy investigated by rotational magnetization curve, and magnetization reversal behaves according to coherent rotation of magnetic moment vector.
• Co-existing FM and AF phases in composite matrix are lead to extraordinary EB behavior.

Nano-composite Co84Zr16N (CZN) films were prepared by reactive co-sputter deposition. As-deposited CZN films have not shown any exchange bias effect. But annealed (390 K) and field cooled samples have shown exchange bias phenomena. The observed exchange bias is attributed to inter-cluster exchange coupling between ferromagnetic and antiferromagnetic nano-composite phase. High resolution transmission electron microscope study reveals that, the CZN films are composed of ordered and crystalline ferromagnetic Cobalt nano-clusters embedded in an antiferromagnetic matrix. X-ray diffraction confirms the poly-crystalline growth of the CZN films with a preferred fcc (622) phase formation. In-plane anisotropy of the exchange biased films was investigated by rotational magnetization curve, and the analysis shows that the magnetization reversal behaves according to the coherent rotation of the magnetic moment vector. Effectively, exchange bias effect in such single layer films could be attributed to co-existing antiferromagnetic and ferromagnetic phase within the single layer. Such single layer nano-composite films can be a possible alternative to the bilayer combination of antiferromagnetic/ferromagnetic exchange biased films and are ideally suited for spintronics and tunnel junction applications.