The role of the interlayer state in the electronic structure of superconducting graphite intercalated compounds

By Gábor Csányi, Peter Littlewood, A. Nevidomskyy, Chris J. Pickard, B. Simons. 2005

217 citations recorded by the source corpus.

Although not an intrinsic superconductor, graphite exhibits superconductivity when intercalated with certain dopants1. Perhaps the most studied of these graphite-based superconductors are the alkali metal–graphite intercalation compounds (GICs) (ref. 2), of which the easiest to fabricate is C8K (ref. 3), with a transition temperature (ref. 2). By increasing the alkali metal concentration (through high-pressure fabrication techniques), the transition temperature can be increased up to 5 K in C2Na (ref. 4). Superconductivity in C6Yb and C6Ca with and 11.5 K, respectively, and at ambient conditions has been observed5. Here we explore the architecture of the states near the Fermi level and identify characteristics of the electronic band structure generic to GICs. In addition to the expected charge transfer from the intercalant atoms to the graphene sheets, resulting from the occupation of the π bands, we find that in all of those—and only those—compounds that superconduct, an interlayer state, which is well-separated from the carbon sheets, also becomes occupied. We show that the energy of the interlayer band is controlled by a combination of its occupancy and the separation between the carbon layers.

Subfields: Electrical and Electronic Engineering, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/e08de0cdeb5fbc08b27aa80590bc54449b436615

How researchers see this paper

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In Electrical and Electronic Engineering

1. M. Arai
2. M. Ghorbani‐Asl
3. A. Ranjbar
4. Yunye Liang
5. Mohammad Khazaei
6. Seiji Yunoki
7. Taizo Sasaki

In Materials Chemistry

1. Seiji Yunoki
2. Mohammad Khazaei
3. M. Arai
4. M. Ghorbani‐Asl
5. M. Calandra
6. A. Ranjbar
7. F. Mauri
8. Yunye Liang

In Mechanical Engineering

1. M. Arai
2. A. Ranjbar
3. Yunye Liang
4. Mohammad Khazaei
5. Seiji Yunoki
6. Taizo Sasaki

Citations in the corpus

• Nearly free electron states in MXenes (2016, background): “Also, the occupied NFE bands play a crucial role in high temperature superconductivity of alkali metals intercalated graphite compounds to facilitate strong electron-phonon coupling [17,18].”
• Phonon-mediated superconductivity in graphene by lithium deposition (2012, background): “Indeed, in superconducting GICs, an intercalant band (interlayer state) occurs at the Fermi leve”