Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
Phys Rev Lett. 2011 Dec 2;107(23):233401. doi: 10.1103/PhysRevLett.107.233401. Epub 2011 Nov 30.
The determination of spin and orbital magnetic moments from the free atom to the bulk phase is an intriguing challenge for nanoscience, in particular, since most magnetic recording materials are based on nanostructures. We present temperature-dependent x-ray magnetic circular dichroism measurements of free Co clusters (N=8-22) from which the intrinsic spin and orbital magnetic moments of noninteracting magnetic nanoparticles have been deduced. An exceptionally strong enhancement of the orbital moment is verified for free magnetic clusters which is 4-6 times larger than the bulk value. Our temperature-dependent measurements reveal that the spin orientation along the external magnetic field is nearly saturated at ~20 K and 7 T, while the orbital orientation is clearly not.
从自由原子到体相，确定自旋和轨道磁矩是纳米科学的一个有趣挑战，特别是因为大多数磁性记录材料都基于纳米结构。我们呈现了自由钴团簇（N=8-22）的温度依赖的 X 射线磁圆二色性测量结果，从中推断出了非相互作用磁性纳米粒子的固有自旋和轨道磁矩。我们验证了自由磁性团簇中轨道磁矩的异常增强，其值比体相值大 4-6 倍。我们的温度依赖测量表明，在外磁场方向上的自旋取向在约 20 K 和 7 T 时几乎饱和，而轨道取向显然没有。
