尖晶石
拉曼光谱
铁磁性
四方晶系
退火(玻璃)
微晶
材料科学
热稳定性
热分解
外延
分析化学(期刊)
薄膜
磁化
结晶学
化学
晶体结构
纳米技术
冶金
磁场
光学
有机化学
物理
量子力学
色谱法
图层(电子)
作者
M. N. Iliev,Punam Silwal,B. Loukya,Ranjan Datta,D. H. Kim,Nikolay P. Todorov,Neha Pachauri,Arunava Gupta
摘要
Epitaxial thin films of spinel NiCo2O4 (NCO) grown on MgAl2O4 (001) substrates are reported to exhibit dramatic changes in the magnetic and transport properties with deposition temperature. While films grown at lower temperatures (<450°C) are ferrimagnetic with metallic characteristics, those grown at higher temperatures are non-magnetic and insulating. Detailed polarized Raman spectroscopy studies indicate that the higher temperature films have close to the ideal inverse spinel cation distribution, Co3+[Ni2+Co3+]O42−, whereas those deposited at lower temperature are characterized by mixed cation/charge distribution at both the tetragonal (A) and octahedral (B) sites. Additionally, temperature-dependent Raman studies demonstrate that, unlike bulk polycrystalline samples, all the NCO films are robust against thermal treatment with full reversibility after annealing at 600°C in oxygen and air. However, partial decomposition is observed after annealing in vacuum.
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