Cobalt monosilicide
 Left- and right-handed B20 crystal structures adopted by CoSi | |
| Names | |
|---|---|
| IUPAC name
Cobalt monosilicide | |
| Identifiers | |
3D model (JSmol) |
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PubChem CID |
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| Properties | |
| CoSi | |
| Molar mass | 87.018 g/mol |
| Density | 6.3 g/cm3 |
| Melting point | 1,415 °C; 2,579 °F; 1,688 K[1] |
| −0.44×10−6 emu/g[2] | |
| Thermal conductivity | 20 W/(m·K)[2] |
| Structure | |
| Cubic, B20 (FeSi type)[3] | |
| P213 (No. 198), cP8 | |
a = 0.44445 nm | |
Formula units (Z) |
4 |
| Hazards | |
| Flash point | Non-flammable |
| Related compounds | |
Other anions |
Cobalt germanide |
Other cations |
Iron silicide Manganese monosilicide |
Related compounds |
Cobalt disilicide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references | |
Cobalt monosilicide (CoSi) is an intermetallic compound and a silicide of cobalt. It is a semimetal with an electrical resistivity of around 1 mΩ·cm.[2] CoSi is also studied as a chiral topological semimetal because its crystal and electronic structures support unconventional chiral quasiparticles and long surface Fermi arcs.[4]
Crystal structure
CoSi crystallizes in the cubic B20, or FeSi-type, structure with four formula units per unit cell. Its space group is P213 (No. 198), and single-crystal X-ray diffraction measurements give a lattice parameter of 0.44445 nm.[3] The structure lacks inversion, mirror, and roto-inversion symmetries and is therefore chiral. Cobalt and silicon atoms form helices of opposite handedness when the crystal is viewed along the [111] direction.[3]
Electronic and magnetic properties
Measurements of the magnetic susceptibility show that CoSi is diamagnetic at high temperatures but becomes paramagnetic below about 25 K, behavior attributed to the formation of local magnetic moments associated with self-doping and deviations from ideal stoichiometry.[5] Its electronic states are moderately affected by electron correlations, and their density near the Fermi level decreases as temperature increases.[2]
Angle-resolved photoemission spectroscopy measurements have identified spin-1 and charge-2 chiral fermions near the Fermi level. Their projections on the (001) surface are connected by Fermi arcs that extend across the surface Brillouin zone.[4] CoSi and alloys formed by partially replacing cobalt with iron or nickel have also been investigated for their thermoelectric and electrical-transport properties.[6]
References
- ↑ Gas, P.; d’Heurle, F. M. (1998). "Diffusion in silicides". In Beke, D. L. (ed.). Landolt-Börnstein - Group III Condensed Matter. Vol. 33A. Springer. pp. 1–38. doi:10.1007/10426818_13. ISBN 3-540-60964-4.
- 1 2 3 4 Dutta, Paromita; Pandey, Sudhir K (10 April 2019). "Effects of correlations and temperature on the electronic structures and related physical properties of FeSi and CoSi: a comprehensive study". Journal of Physics: Condensed Matter. 31 (14): 145602. Bibcode:2019JPCM...31n5602D. doi:10.1088/1361-648X/aafdce. PMID 30634173. S2CID 58668682.
- 1 2 3 Li, Hang; Xu, Sheng; Rao, Zhi-Cheng; et al. (3 December 2019). "Chiral fermion reversal in chiral crystals". Nature Communications. 10 (1) 5505. arXiv:1912.02383. Bibcode:2019NatCo..10.5505L. doi:10.1038/s41467-019-13435-4. PMC 6890713. PMID 31796737.
- 1 2 Rao, Zhicheng; Li, Hang; Zhang, Tiantian; et al. (20 March 2019). "Observation of unconventional chiral fermions with long Fermi arcs in CoSi". Nature. 567 (7749): 496–499. arXiv:1901.03358. Bibcode:2019Natur.567..496R. doi:10.1038/s41586-019-1031-8. PMID 30894751.
- ↑ Stishov, Sergei M.; Petrova, Alla E.; Sidorov, Vladimir A.; Menzel, Dirk (23 August 2012). "Self-doping effects in cobalt silicide CoSi: Electrical, magnetic, elastic, and thermodynamic properties". Physical Review B. 86 (6) 064433. Bibcode:2012PhRvB..86f4433S. doi:10.1103/PhysRevB.86.064433.
- ↑ Antonov, A. S.; Novikov, S. V.; Pshenay-Severin, D. A.; Burkov, A. T. (23 May 2019). "Thermoelectric Properties of Cobalt Monosilicide and Its Alloys". Semiconductors. 53 (5): 667–672. Bibcode:2019Semic..53..667A. doi:10.1134/S1063782619050038.