Magnetic and electrical characteristics in dense Fe–Ni alloy cluster-assembled films prepared by energetic cluster deposition

Abstract

Fe–Ni alloy cluster-assembled films were obtained by a plasma–gas-condensation-type cluster-deposition method. We studied the magnetic and electrical properties of these assemblies prepared on an electrically grounded substrate [bias voltage (Va) = 0 kV] and on a negatively biased substrate (Va = −20 kV). The packing density and saturation magnetization per volume, Ms, are much larger for the assemblies prepared at Va = −20 kV than those prepared at Va = 0 kV, while the magnetic coercivity, Hc, and electrical resistivity, ρ, are much lower for the assemblies prepared at Va = −20 kV than those prepared at Va = 0 kV. For Ni-rich Fe–Ni alloy cluster-assembled films obtained at Va = −20 kV, the Hc values can become smaller than 160 A/m (the precision limit of our superconducting quantum interference device magnetometer) by adjusting the initial cluster size. The magnetic and electrical properties of Fe–Ni cluster-assembled films are much improved in comparison with those of pure Fe cluster-assembled films.

High Frequency Magnetic Property of Dense Fe<SUB>22</SUB>Ni<SUB>78</SUB> Cluster Assembled Films

“…5, M S increases from 0.26 to 0.81 Wb/m 2 as V A increases from 0 to 20 kV for the Fe 22 Ni 78 clusterassembled films prepared with R Ar ¼ 3:7 Â 10 À4 mol/s and R O 2 ¼ 0 mol/s, probably because M S is proportional to the packing fraction of clusters which increases with V A . 4,6,7) In our previous works, 4,6) we estimated the volume fractions of Fe and Fe-Co cluster assembled films from their volumes and weights. The volume fractions were estimated to be 31-35% at V A ¼ 0 kV, and 83-86% at V A ¼ 20 kV.…”

“…High-density Fe, Fe-Co and FeNi cluster assembled films thus obtained reveal a high cluster packing density of about 85%. 4,6,7) The values are still one order larger than those of the bulk alloys because a lot of boundaries between clusters can scatter conduction electrons. In these high density ferromagnetic cluster assembled films M S is large and the magnetic coercivity, H C , becomes negligibly small because many ferromagnetic clusters are ferromagnetically coupled by exchange interactions.…”

High Frequency Characteristics of Fe65Co35 Alloy Cluster-Assembled Films Prepared by Energetic Cluster Deposition

“…Therefore, in order to improve high frequency magnetic characteristics of the materials, new materials with high resistivity, high M s , and good soft magnetic property are desired. In our previous work, [10][11][12] high-density Fe, Fe-Co and Fe-Ni cluster assembled films by energetic cluster deposition revealed a good soft magnetic behavior and a high electric resistivity. Such a soft magnetic nano-clusterassembled film is supposed to be ideal high-permeability material for high frequency uses.…”

Formic Acid Oxidation Catalytic Properties of Pd Nanoclusters Prepared by Physical Vapor Deposition

“…In the PVD synthesis, Pd NCs are synthesized under the high vacuum and inert gas condition in the plasma-gas-condensation clusters deposition apparatus, which protects them away from surface pollution and oxidation. On the other hand, the as-prepared samples were cluster-assembled Pd films whose packing density (P) was only about 30% of bulk Pd [11], and had a narrow particles size distribution with an average size of 5.8 nm. Besides, Pd NCs, directly deposited onto the GCP, have high adhesion strength and perfect contact between adjacent clusters even without additives.…”