Transition from zero-dimensional superparamagnetism to two-dimensional ferromagnetism of Co clusters on Au(111)

被引:89
作者
Padovani, S [1 ]
Chado, I [1 ]
Scheurer, F [1 ]
Bucher, JP [1 ]
机构
[1] Univ Strasbourg 1, Inst Phys & Chim Mat Strasbourg, UMR 7504 CNRS, F-67037 Strasbourg, France
关键词
D O I
10.1103/PhysRevB.59.11887
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The early growth stages of Co structures on Au(lll) have been analyzed by scanning tunneling microscopy and their magnetic properties simultaneously measured, in situ, by Ken effect and, ex sial by superconducting quantum interference device. With increasing cobalt coverage, cobalt clusters, organized on the lattice of the 22 x root 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 OD cluster superparamagnetism, to 1D Ising behavior and finally to 2D ferromagnetism as a function of cobalt coverage, in good agreement with experimental results. [S0163-1829(99)04617-2].
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页码:11887 / 11891
页数:5
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