Pulsed Laser Deposition of NiO/Pt and Fe/NiO/Pt Thin-Film Heterostructures for THz Applications

Thin films of NiO, Fe, and Pt and NiO/Pt, Fe/NiO/Pt heterostructures are fabricated using the pulsed laser deposition in a droplet-free mode with the ablation of metal targets on single-crystal sapphire substrates with the orientation (0001) at room temperature. The heterostructures are obtained by the sequential deposition of layers within in a single technological cycle. The structural, optical, and electrophysical properties and surface morphology of the obtained films and heterostructures are studied. The presence of the 2M mode is established in the Raman spectra, which confirms antiferromagnetic ordering in the NiO layers in the synthesized heterostructures. The X-ray diffraction spectra of both the individual NiO films and heterostructures demonstrate NiO (111) diffraction peaks, which confirms the high crystalline perfection of the films synthesized at room temperature without additional annealing. Terahertz radiation generation is achieved in the Fe/NiO/Pt heterostructure upon excitation by femtosecond laser pulses.