In-depth structural and magnetic study of Ni/NiO epitaxial thin films on single crystalline sapphire grown using pulsed laser deposition

The crystallographic orientation plays a significant role in magnetic heterostructure devices, especially in the arena of spintronic devices. In terms of magnetic property, domain orientation is solely dependent on the structural homogeneity. This research work deals with the development of epitaxial thin films of Ni/NiO on single-crystalline sapphire (0006) substrate. PLD was used at 650°C in constant oxygen pressure of 0.01 mbar to deposit films. Phase mixture of Ni/NiO in the thin films was achieved via reduction annealing. XRD data shows preferential growth of NiO on sapphire along the (111) plane (peak at 37.25°), sharp peak of Ni at 44.4° indicates a handful amount of NiO convert to Ni phase. Crystallographic orientation of NiO was analyzed by phi scan and pole figure technique. TEM-EDS images show the surface homogeneity with presence of both Ni and NiO on the film. Magnetic force microscopy and ferromagnetic resonance indicated the ferromagnetic nature of the film. Temperature and field dependent magnetization data collected using SQUID magnetometer show ferromagnetism and antiferromagnetism in Ni and NiO films, respectively. Spin canting has been observed in phase mixture, holding a potential wide range magnetic exchange coupled phenomena.