Magnetic properties of thin‐film Ag+iron‐oxide granular metals
作者:
R. D. Shull,
U. Atzmony,
A. J. Shapiro,
L. J. Swartzendruber,
L. H. Bennett,
W. J. Green,
K. Moorjani,
期刊:
Journal of Applied Physics
(AIP Available online 1988)
卷期:
Volume 63,
issue 8
页码: 4261-4263
ISSN:0021-8979
年代: 1988
DOI:10.1063/1.341146
出版商: AIP
数据来源: AIP
摘要:
The magnetic properties of iron‐oxide particulates dispersed in silver (prepared by rf diode sputtering silver and iron oxide over a wide composition range) have been investigated using the Mo¨ssbauer effect, electron microscopy, and vibrating sample magnetometry. The sputtered films are nanocrystalline mixtures of immiscible particles of the two constituents (even when only a very small amount of silver is present). At room temperature, the Mo¨ssbauer effect data show that for most compositions (even those with low silver content) the majority of the film is superparamagnetic, with the fraction of material in the superparamagnetic state increasing with increasing Ag content. Consistent with these results, very narrow hysteresis loops were observed. On decreasing the temperature to near 100 K, the fraction of material in the superparamagnetic state decreased and the magnetically ordered component increased. Electron diffraction patterns clearly showed the presence of polycrystalline Ag and Fe3O4in the films, but composition analysis (0.03 &mgr;m resolution) was unable to separate these regions.
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