Synthesis and magnetotransport studies of CrO₂-Al₂O₃ composite films

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• 作者：Caiping Zhang ; Songbo Zhang ; Faming Li ; Yinbo Fan ; Xiaoling Wang ; Gehui Wen ; ^{phghwen@aliyun.com" class="auth_mail} ; ^{wengh@jlu.edu.cn" class="auth_mail}
• 关键词：CrO2 ; Thin films ; Magnetoresistance ; Magnetic materials ; Chemical vapor deposition
• 刊名：Materials Letters
• 出版年：15 April, 2014
• 年：2014
• 卷：121
• 期：Complete
• 页码：156-158
• 全文大小：787 K

文摘

CrO₂-Al₂O₃ composite films were deposited on Si(100) substrates by the atmospheric pressure chemical vapor deposition method using CrO₃ and AlBr₃ as precursors. The CrO₂-Al₂O₃ composite films consist of large CrO₂ grains and Al₂O₃ nanoparticles. The composition of the films was controlled by adjusting the temperature of CrO₃ during deposition. The CrO₂-Al₂O₃ composite film with Al₂O₃ content of 0.38 (molar fraction) shows insulator-metal transition. Below 120 K, it is insulator and the temperature dependence of its resistance can be well explained by the fluctuation-induced tunneling model; above 175 K, it is metallic. It shows large intergrain tunneling magnetoresistance at low temperature, which reaches 鈭?5.2% at 5 K and 50 kOe. While at high temperature the intergrain tunneling magnetoresistance in the film nearly disappears, and the film shows a small linear magnetoresistance, which should be due to the double-exchange mechanism in CrO₂.