Soldano Caterina, Kar Swastik, Talapatra Saikat, Nayak Saroj, Ajayan Pulickel M
Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
Nano Lett. 2008 Dec;8(12):4498-505. doi: 10.1021/nl802456t.
The ultimate conductometric sensor for ferromagnetic activity of nanoscale magnetic materials could be a single carbon nanotube. We show that the electrical conductance of an individual carbon nanotube is sensitive to magnetic transitions of nanoscale magnets embedded inside it. To establish this, multiwall carbon nanotubes were impregnated with cobalt nanoclusters. Temperature dependence of conductance (5 K < T <300 K) of these nanotubes shows the usual Lüttinger-liquid power law behavior at higher temperatures and an onset of Coulomb blockade at lower temperatures. At the lowest temperature (T approximately 6 K), the differential conductance (dI/dV versus V) develops aperiodic fluctuations under an external magnetic field B, the rms amplitude of which grows with the magnitude of the field itself. Low-temperature magnetoconductance, studied as function of temperature and bias, can be interpreted in terms of weak antilocalization effects due to the presence of the magnetized clusters. The temperature dependence of magnetoconductance further presents a "peak"-like feature and slow dynamics around T =55 K, which depend on the magnitude and history of the applied B field. These observations indicate a sensitivity of electronic transport in the multiwall nanotubes to the dynamics of nanoscale magnets at low temperature.
用于纳米级磁性材料铁磁活性的终极电导传感器可能是单个碳纳米管。我们表明，单个碳纳米管的电导对嵌入其中的纳米级磁体的磁转变敏感。为了证实这一点，将多壁碳纳米管浸渍钴纳米团簇。这些纳米管的电导随温度的变化（5K＜T＜300K）在较高温度下呈现出通常的卢廷格液体幂律行为，在较低温度下出现库仑阻塞。在最低温度（T约为6K）时，微分电导（dI/dV对V）在外部磁场B下出现非周期性波动，其均方根幅度随磁场强度本身的增加而增大。作为温度和偏置函数研究的低温磁电导，可以根据由于磁化团簇的存在而产生的弱反局域化效应来解释。磁电导的温度依赖性在T = 55K附近进一步呈现出“峰值”状特征和缓慢动力学，这取决于所施加B场的大小和历史。这些观察结果表明，多壁纳米管中的电子输运对低温下纳米级磁体的动力学敏感。
