저온에서 (001)MgAl2O4 기판에 증착한 에피탁시 NiCo2O4 박막의 준강자성 및 금속성

Using pulsed laser deposition, we deposited (001) NiCo2O4 films on (001) MgAl2O4 substrates while fixing other deposition parameters and reducing the deposition temperature from 320 ^◦C to 100 ^◦C. As the deposition temperature decreased to 150 ^◦C, X-ray diffraction patterns indicated a decrease in the out-of-plane lattice constant from 8.186 Å to 8.142 Å. Conversely, at a deposition temperature of 100 ^◦C, no film peak was observed, supporting the amorphous film. The polar magneto-optical Kerr effect revealed that the coercivity was approximately 1200 Oe in the film grown at 320 ^◦C and showed a significant decrease to around 200–300 Oe at the deposition temperatures below 250 ^◦C, with no observable perpendicular magnetic anisotropy at the deposition temperature of 100 ^◦C. The temperature at which the metal-insulator transition occurred was around 500 K in the film grown at 250 ^◦C, and exhibited weakened metallic behavior as the deposition temperature decreased to 150 ^◦C. This work demonstrated that even at a low deposition temperature of 150 ^◦C, the epitaxial NiCo2O4 film exhibited tetragonal lattice strain, perpendicular magnetic anisotropy, and metallic properties.