Sangiao Soraya, Magén César, Mofakhami Darius, de Loubens Grégoire, De Teresa José María
Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, 50018 Zaragoza, Spain.
Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain.
Beilstein J Nanotechnol. 2017 Oct 9;8:2106-2115. doi: 10.3762/bjnano.8.210. eCollection 2017.
In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID). The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM) experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm. Electron holography measurements show the formation of a magnetic vortex state in remanence, which nicely agrees with magnetic hysteresis loops performed by local magnetometry showing negligible remanent magnetization. As investigated by local magnetometry, optimal behavior for high-resolution MRFM has been found for cobalt nanospheres with a diameter of ≈200 nm, which present atomic cobalt content of ≈83 atom % and saturation magnetization of 10 A/m, around 70% of the bulk value. These results represent the first comprehensive investigation of the magnetic properties of cobalt nanospheres grown by FEBID for application in MRFM.
在这项工作中，我们详细研究了通过聚焦电子束诱导沉积（FEBID）在悬臂尖端生长的钴纳米球的磁性。悬臂极其柔软，钴纳米球针对磁共振力显微镜（MRFM）实验进行了优化，这意味着钴纳米球必须尽可能小，同时保持高饱和磁化强度。研究发现，对于直径小于300 nm的纳米球，其钴含量和相应的饱和磁化强度会降低。电子全息测量显示在剩余状态下形成了磁涡旋态，这与通过局部磁强计进行的磁滞回线测量结果非常吻合，后者显示剩余磁化强度可忽略不计。通过局部磁强计研究发现，对于直径约为200 nm的钴纳米球，在高分辨率MRFM中表现出最佳性能，其原子钴含量约为83原子%，饱和磁化强度为10 A/m，约为体材料值的70%。这些结果代表了对通过FEBID生长的钴纳米球用于MRFM的磁性进行的首次全面研究。
