Leibniz Institute for Solid State and Materials Research IFW Dresden, Helmholtzstr. 20, 01069, Dresden, Germany.
Institut für Festkörperphysik, Technische Universität Dresden, 01062, Dresden, Germany.
Sci Rep. 2017 Aug 21;7(1):8881. doi: 10.1038/s41598-017-08340-z.
The investigation of properties of nanoparticles is an important task to pave the way for progress and new applications in many fields of research like biotechnology, medicine and magnetic storage techniques. The study of nanoparticles with ever decreasing size is a challenge for commonly employed methods and techniques. It requires increasingly complex measurement setups, often low temperatures and a size reduction of the respective sensors to achieve the necessary sensitivity and resolution. Here, we present results on how magnetic properties of individual nanoparticles can be measured at room temperature and with a conventional scanning force microscopy setup combined with a co-resonant cantilever magnetometry approach. We investigate individual CoFeGa Heusler nanoparticles with diameters of the order of 35 nm encapsulated in carbon nanotubes. We observed, for the first time, magnetic switching of these nanoparticles in an external magnetic field by simple laser deflection detection. Furthermore, we were able to deduce magnetic properties of these nanoparticles which are in good agreement with previous results obtained with large nanoparticle ensembles in other experiments. In order to do this, we expand the analytical description of the frequency shift signal in cantilever magnetometry to a more general formulation, taking unaligned sensor oscillation directions with respect to the magnetic field into account.
研究纳米粒子的性质对于推进生物技术、医学和磁存储技术等多个研究领域的发展和新应用具有重要意义。随着尺寸不断减小，对通常使用的方法和技术的研究也提出了挑战。这需要越来越复杂的测量装置，通常需要低温条件和相应传感器的尺寸减小，以实现必要的灵敏度和分辨率。在这里，我们介绍了如何在室温下使用传统的扫描力显微镜设置和共共振悬臂磁强计方法来测量单个纳米粒子的磁性能。我们研究了直径约为 35nm 的封装在碳纳米管中的单个 CoFeGa Heusler 纳米粒子。我们首次观察到这些纳米粒子在外磁场中的磁开关，通过简单的激光偏转检测即可实现。此外，我们还能够推导出这些纳米粒子的磁性能，这些性能与以前在其他实验中用大的纳米粒子集合并获得的结果非常吻合。为了做到这一点，我们将悬臂磁强计中频率位移信号的分析描述扩展到更一般的公式，考虑到传感器相对于磁场的非对齐振荡方向。
