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Magnetism at single isolated iron atoms implanted in graphite
R Sielemann1, Y Kobayashi, Y Yoshida
1Hahn-Meitner-Institut Berlin GmbH, 14109 Berlin, Germany.
Physical Review Letters
|October 15, 2008
Summary
Iron-57 Mössbauer spectroscopy reveals atomic-scale magnetism in graphite. Implantation of iron-57 into highly oriented pyrolytic graphite (HOPG) induces magnetic ordering, evidenced by a significant hyperfine field.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nuclear Physics
Background:
- Highly oriented pyrolytic graphite (HOPG) is typically considered diamagnetic.
- Recent studies have indicated magnetic effects in HOPG, but without atomic-scale resolution.
- Understanding magnetism in carbon-based materials is crucial for advanced electronics and spintronics.
Purpose of the Study:
- To investigate the presence and nature of magnetism at the atomic scale in HOPG.
- To determine if iron-57 (57Fe) implantation can induce magnetic ordering in graphite.
- To characterize the magnetic interactions at the atomic level using Mössbauer spectroscopy.
Main Methods:
- Implantation of 57Fe probe atoms into highly oriented pyrolytic graphite (HOPG).
- Mössbauer spectroscopy measurements at 14 K to analyze hyperfine interactions.
- Analysis of combined magnetic and quadrupole interactions to determine magnetic field and local environment.
Main Results:
- Mössbauer spectra exhibited a combined magnetic and quadrupole interaction.
- A magnetic hyperfine field (Bhf) of 32.6 Tesla was measured at 14 K.
- Evidence for atomic-scale magnetism induced by 57Fe implantation in HOPG was established.
Conclusions:
- The study provides the first experimental evidence of atomic-scale magnetism in graphite.
- Magnetic ordering is attributed to the coupling of the Fe magnetic moment with implantation-induced defects.
- This finding opens new avenues for exploring magnetic phenomena in nominally diamagnetic materials.
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