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Enhanced high-pressure superconductivity and local structure of theBa8Si46clathrate
- Source :
- Physical Review B. 94
- Publication Year :
- 2016
- Publisher :
- American Physical Society (APS), 2016.
-
Abstract
- The high-pressure superconducting properties and the local structure of the Ba8Si46 clathrate have been studied using electrical resistance and x-ray absorption spectroscopy measurements up to more than 20 GPa. At pressures above 10–13 GPa, corresponding to a well-known volume collapse phase transformation, a sudden increase in the critical temperature leads to a maximum value of the superconducting critical temperature Tc of ∼8.5–9 K at 20 GPa. In the low-pressure clathrate phase, the superconducting critical temperature decreases as pressure is applied with an electron-phonon coupling constant λ=1.1 derived from the temperature evolution of the electrical resistance at different pressures. A progressive disorder in the Ba-Si correlations in the Ba@Si24 cages of the structure is observed for pressures beyond ∼5 GPa. These observations exclude a structural homothecy at the volume collapse transition. The high-pressure collapsed phase of Ba8Si46 is then associated with local structural changes and shows enhanced superconducting properties.
- Subjects :
- Coupling constant
Superconductivity
Materials science
Condensed matter physics
Absorption spectroscopy
Clathrate hydrate
02 engineering and technology
021001 nanoscience & nanotechnology
01 natural sciences
Local structure
Condensed Matter::Materials Science
Electrical resistance and conductance
Volume (thermodynamics)
Condensed Matter::Superconductivity
Phase (matter)
0103 physical sciences
010306 general physics
0210 nano-technology
Subjects
Details
- ISSN :
- 24699969 and 24699950
- Volume :
- 94
- Database :
- OpenAIRE
- Journal :
- Physical Review B
- Accession number :
- edsair.doi...........51f72ed40c9925f1f68f5bad8f12a7f1