標題: Origin of metallic behavior in NiCo2O4 ferrimagnet
作者: Bitla, Yugandhar
Chin, Yi-Ying
Lin, Jheng-Cyuan
Van, Chien Nguyen
Liu, Ruirui
Zhu, Yuanmin
Liu, Heng-Jui
Zhan, Qian
Lin, Hong-Ji
Chen, Chien-Te
Chu, Ying-Hao
He, Qing
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 15-Oct-2015
摘要: Predicting and understanding the cation distribution in spinels has been one of the most interesting problems in materials science. The present work investigates the effect of cation redistribution on the structural, electrical, optical and magnetic properties of mixed-valent inverse spinel NiCo2O4(NCO) thin films. It is observed that the films grown at low temperatures (T < 400 degrees C) exhibit metallic behavior while that grown at higher temperatures (T > 400 degrees C) are insulators with lower ferrimagnetic-paramagnetic phase transition temperature. So far, n-type Fe3O4 has been used as a conducting layer for the spinel thin films based devices and the search for a p-type counterpart still remains elusive. The inherent coexistence and coupling of ferrimagnetic order and the metallic nature in p-type NCO makes it a promising candidate for spintronic devices. Detailed X-ray Absorption and X-ray Magnetic Circular Dichroism studies revealed a strong correlation between the mixed-valent cation distribution and the resulting ferrimagnetic-metallic/insulating behavior. Our study clearly demonstrates that it is the concentration of Ni3+ ions and the Ni3+-O-2-Ni2+ double exchange interaction that is crucial in dictating the metallic behavior in NCO ferrimagnet. The metal-insulator and the associated magnetic order-disorder transitions can be tuned by the degree of cation site disorder via growth conditions.
URI: http://dx.doi.org/10.1038/srep15201
http://hdl.handle.net/11536/128412
ISSN: 2045-2322
DOI: 10.1038/srep15201
期刊: SCIENTIFIC REPORTS
Volume: 5
起始頁: 0
結束頁: 0
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