Electrical and Magnetic Properties Modification in Heavy Ion Irradiated Nanograin NixCo(3鈥?i>x)O4 Films

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• 作者：John S. McCloy ; Weilin Jiang ; Wendy Bennett ; Mark Engelhard ; Jeffrey Lindemuth ; Narendra Parmar ; Gregory J. Exarhos
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 1, 2015
• 年：2015
• 卷：119
• 期：39
• 页码：22465-22476
• 全文大小：681K
• ISSN：1932-7455

文摘

Reactively sputtered Ni_xCo_(3鈥?i>x)O₄ films (x = 1.5, 1.0, and 0.75) were grown and subsequently irradiated with 5.5 MeV Si⁺ ions to investigate effects of lattice-site and charge state distribution. Films were characterized before and after irradiation by X-ray diffraction, X-ray photoemission spectroscopy, Rutherford backscattering spectroscopy, electric resistivity measurements, and temperature-dependent AC and DC magnetometry. Results indicate that ion irradiation induces oxygen loss, partial reduction of nickel, and an increase in both low-temperature ferrimagnetism and room-temperature conductivity. Frequency-dependent AC magnetic susceptibility measurements indicate a spin-glass-like transition at low temperature which moves to higher temperature after irradiation. Significance of the charge transfer for magnetism and conduction in a mixed spinel with Co²⁺, Co³⁺, Ni²⁺, and Ni³⁺ in tetrahedral and octahedral sites is discussed.