High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB6

By D. Edwards, M. Katsnelson. 2006

137 citations recorded by the source corpus.

Ferromagnetism with high Curie temperature Tc, well above room temperature, and very small saturation moment has been reported in various carbon and boron systems. It is argued that the magnetization must be very inhomogeneous with only a small fraction of the sample ferromagnetically ordered. It is shown that a possible source of high Tc within the ferromagnetic regions is itinerant electrons occupying a narrow impurity band. Correlation effects do not reduce the effective interaction which enters the Stoner criterion in the same way as in a bulk band. It is also shown how, in the impurity band case, spin wave excitations may not be effective in lowering Tc below its value given by Stoner theory. These ideas are applied to CaB6 and a thorough review of the experimental situation in this material is given. It is suggested that the intrinsic magnetism of the B2 and O2 dimers might be exploited in suitable structures containing these elements.

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Geophysics

View Paper: https://www.semanticscholar.org/paper/cf5149d06c4bb01cd89234ac19d34cf4db13957d

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In Condensed Matter Physics

1. M. Katsnelson
2. O. Yazyev
3. A. Lichtenstein
4. V. Irkhin
5. R. D. Groot
6. L. Chioncel

In Electronic, Optical and Magnetic Materials

1. O. Yazyev
2. A. Lichtenstein
3. V. Irkhin
4. R. D. Groot
5. M. Katsnelson
6. L. Chioncel

In Geophysics

1. O. Yazyev

Citations in the corpus

• Half-metallic ferromagnets: From band structure to many-body effects (2007, background): “Another perspective direction is the use of electron-structure calculations to search essentially new types of HMF like sp electron (or anionic) magnets (Attema et al., 2005; Edwards and Katsnelson, 2006).”
• Emergence of magnetism in graphene materials and nanostructures (2010, background): “In addition, materials based sp-elements are expected to have high magnitudes of the spin-wave stiffness (Edwards and Katsnelson, 2006) and, thus, nanostructures made of these elements would possess higher Curie temperatures or spin correlation lengths (Yazyev and Katsnelson, 2008).”