Room-Temperature Ferromagnetism and Extraordinary Hall Effect in Nanostructured Q-Carbon: Implications for Potential Spintronic Devices
Room-Temperature Ferromagnetism and Extraordinary Hall Effect in Nanostructured Q-Carbon: Implications for Potential Spintronic Devices
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DOI：
10.1021/acsanm.7b00253
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发表时间：
2018-02-01
影响因子：
5.9
通讯作者：
Narayan, Jagdish
中科院分区：
文献类型：
--
作者：
Bhaumik, Anagh;Nori, Sudhakar;Narayan, Jagdish
我们报道了在未掺杂的Q - 碳中存在异常霍尔效应和室温铁磁性，这种Q - 碳是通过纳秒脉冲激光熔化及随后的淬火过程形成的。通过对Q - 碳薄膜详细的结构 - 性能关联研究，我们表明费米能级附近过量的未成对电子产生了有趣的磁学和电学性质。对Q - 碳中异常霍尔效应的分析遵循非经典的“侧向跳跃”电子散射机制。等温场相关的磁化曲线证实了Q - 碳在室温下具有铁磁性，在300 K时具有有限的矫顽力，通过使用修正的布洛赫定律对实验数据进行拟合外推得到居里温度为570 K。高分辨率扫描电子显微镜和透射电子显微镜清楚地展示了Q - 碳的形成以及它随后向单晶金刚石的转变。此外，基于异常霍尔系数与磁场的实验，我们发现Q - 碳在10到300 K的整个温度范围内具有n型导电性。Q - 碳这些有趣的磁学和电子输运性质的发现表明，利用过冷工艺的非平衡合成技术可用于制造物理性质和功能大幅增强的新材料。在Q - 碳中观察到的显著的室温铁磁性以及异常霍尔效应将在碳基自旋电子学中找到潜在应用。
We report extraordinary Hall effect and room temperature ferromagnetism in undoped Q:carbon, which is formed by nanosecond pulsed laser melting and subsequent quenching process. Through detailed structure-property correlations in Q-carbon thin films, we show the excess amount of unpaired electrons near the Fermi energy level give rise to interesting magnetic and electrical properties. The analysis of the extraordinary Hall effect in Q-carbon follows nonclassical "side jump" electronic scattering mechanism. The isothermal field dependent magnetization plots confirm room-temperature ferromagnetism in Q-carbon with a finite coercivity at 300 K and a Curie temperature of 570 K, obtained by the extrapolation of the fits to experimental data using modified Bloch's law. High-resolution scanning electron microscopy and transmission electron microscopy clearly illustrate the formation of Q-carbon and its subsequent conversion to single-crystalline diamond. Further, we found n-type conductivity in Q-carbon in the entire temperature range from 10 to 300 K based on the extraordinary Hall coefficient versus magnetic field experiments. This discovery of interesting magnetic and electron transport properties of Q-carbon show that nonequilibrium synthesis technique using super undercooling process can be used to fabricate new materials with greatly enhanced physical properties and functionalities. The observed robust room-temperature ferromagnetism coupled with extraordinary Hall effect in Q-carbon will find potential applications in carbon-based spintronics.