Superparamagnetic behavior of ultrathin Fe films grown on Al{sub 2}O{sub 3} (0001) substrates.
We have studied superparamagnetic behavior of ultrathin Fe films grown on an Al{sub 2}O{sub 3}(0001) substrate at various growth temperatures. It is demonstrated that 1-nm-thick Fe films are in the superparamagnetic state, and the blocking temperature is strongly dependent on the growth temperature. The blocking temperature has a minimum value of 30 K for a growth temperature of 473 K, while it is -70 K at other growth temperatures. In order to clarify the behavior, we consider the Fe growth mechanism and the magnetic interactions between Fe particles. Fe grows as three-dimensional islands at all temperatures studied and forms particles. The volume of the particles is observed via atomic force microscopy to increase with increasing growth temperature. In the case of growth at 323 and 373 K, Fe forms small particles that are close together and that interact with each other. For growth at 673 and 773 K, Fe forms relatively large particles and the magnetic properties are dominated by the individual particles.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); FOR
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 961421
- Report Number(s):
- ANL/MSD/JA-47591; JAPIAU; TRN: US201012%%1484
- Journal Information:
- J. Appl. Phys., Vol. 94, Issue 12 ; Dec. 15, 2003; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- ENGLISH
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