TRANSITION FROM ZERO-DIMENSIONAL SUPERPARAMAGNETISM TO TWO-DIMENSIONAL FERROMAGNETISM OF CO CLUSTERS ON AU(111)
TRANSITION FROM ZERO-DIMENSIONAL SUPERPARAMAGNETISM TO TWO-DIMENSIONAL FERROMAGNETISM OF CO CLUSTERS ON AU(111)
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AU(111)上Co团簇从零维超顺磁性到二维铁磁性的转变
DOI：
10.1103/physrevb.59.11887
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发表时间：
1999
影响因子：
3.7
通讯作者：
J. Bucher
中科院分区：
文献类型：
--
作者：
S. Padovani;I. Chado;F. Scheurer;J. Bucher
用扫描隧道显微镜分析了Co结构在Au(111)面上生长的早期阶段，并用Kerr效应和超导量子干涉仪同时进行了原位和非原位磁性测量。随着钴覆盖率的增加，在22×3之字形重构的晶格上排列的钴团簇在1.0单分子层(ML)的覆盖率下聚合成一维(1D)链，然后在2ML处形成几乎连续的薄膜。虽然这种明确的生长模式是由松弛的金表面之字形重构处的有序点位错的存在所决定的，但当存在大范围的应变线性重构时，也观察到了反常的形核和生长。然后必须考虑两族团簇，这对磁性有重要影响。当只存在之字形重建时，当钴的覆盖率为1.6ML时，观察到长程2D铁磁性的开始。各向异性Heisenberg模型的蒙特卡罗模拟很好地描述了从0D团簇超顺磁性到1D Ising行为，最后到2D铁磁性的转变，这与实验结果很好地一致。
The early growth stages of Co structures on Au (111) have been analyzed by scanning tunneling microscopy and their magnetic properties simultaneously measured, in situ, by Kerr effect and, ex situ by superconducting quantum interference device. With increasing cobalt coverage, cobalt clusters, organized on the lattice of the 22× 3 zigzag reconstruction coalesce into one-dimensional (1D) chains at a coverage of 1.0 monolayer (ML) and then into a nearly continuous film at 2 ML. While this well-defined growth mode is dictated by the presence of ordered point dislocations at the zigzag reconstruction of the relaxed gold surface, anomalous nucleation and growth is also observed when large domains of strained linear reconstructions are present. Two families of clusters must then be considered with important consequences for magnetic properties. When only the zigzag reconstruction is present, the onset of long-range, 2D ferromagnetism is observed at a coverage of 1.6 ML of cobalt. A Monte Carlo simulation of an anisotropic Heisenberg model describes well transitions from 0D cluster superparamagnetism, to 1D Ising behavior and finally to 2D ferromagnetism as a function of cobalt coverage, in good agreement with experimental results.