Spin-Glass-Like Behaviour in Nanocrystalline Fe

✍ Scribed by Del Bianco, L. ;Hernando, A. ;Fiorani, D.

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 86 KB
• Volume: 189
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/1521-396x(200202)189:2<533::aid-pssa533>3.0.co;2-o

✦ Synopsis

Pure Fe powder was milled down to about 10 nm crystal size. In the as-milled sample, Mo ¨ssbauer spectroscopy reveals the presence of two phases: crystallites and grain boundaries, the latter with a strongly disordered atomic configuration. The microstructural features affect the magnetisation behaviour, as measured in the 5-250 K range at low and saturating magnetic field. Low field measurements indicate a transition from a high-temperature ferromagnetic state to a low-temperature spin-disordered state. This has been explained as a consequence of the spin freezing at the grain boundaries which drastically decreases the exchange coupling between the grains.