Synchrotron radiation studies of mass-selected Fe nanoclusters deposited in situ

被引:7
作者
Binns, C [1 ]
Baker, SH
Maher, MJ
Thornton, SC
Louch, S
Dhesi, SS
Brookes, NB
机构
[1] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England
[2] European Synchrotron Radiat Facil, F-38043 Grenoble, France
关键词
D O I
10.1007/s100530170089
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
A portable UHV-compatible gas aggregation cluster source, capable of depositing clean mass-selected nanoclusters in situ, has been used at synchrotron radiation facilities to study the magnetic behaviour of exposed and Co-coated Fe clusters in the size range 250 to 540 atoms. X-ray magnetic circular dichroism (XMCD) studies of isolated and exposed 250-atom clusters show a 10% enhancement in the spin magnetic moment and a 75% enhancement in the orbital magnetic moment relative to bulk Fe. The spin moment monotonically approaches the bulk value with increasing cluster size but the orbital moment does not measurably decay till the cluster size is above similar to 400 atoms. The total, magnetic moments for the supported particles though higher than the bulk value are less than those measured in free clusters. Coating the deposited particles with Co in situ increases the spin moment by a further 10% producing a total moment per atom close to the free cluster value. At low coverages the deposited clusters are superparamagnetic at temperatures above 10 K but a magnetic remanence at higher temperature emerges as the cluster density increases and for cluster films with a thickness greater than 50 Angstrom (i.e. 2-3 layers of clusters) the remanence becomes greater than that of an Fe film of the same thickness produced by a conventional deposition source. Thick cluster-assembled film show a strong in-plane anisotropy.
引用
收藏
页码:189 / 192
页数:4
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