XAFS study on a pressure-induced superconductor Cs3C60 under high pressure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Chemistry

Background:

• Cesium fulleride (Cs3C60) exhibits pressure-induced superconductivity, a phenomenon not fully understood.
• Understanding the structural evolution under pressure is crucial for elucidating the mechanism of superconductivity in fullerene compounds.

Purpose of the Study:

• To investigate the structural properties of Cs3C60 under high pressure using X-ray absorption fine structure (XAFS) spectroscopy.
• To correlate structural changes with the onset of superconductivity in Cs3C60.
• To validate high-pressure XAFS as a reliable method for studying fullerene superconductors.

Main Methods:

• Measurements of Cs K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were performed on Cs3C60.
• High pressures (21 and 34 kbar) were achieved using a diamond anvil cell (DAC).
• Data analysis involved determining interatomic distances and mean square displacements.

Main Results:

• The interatomic distances and mean square displacements between Cs and C atoms were determined under high pressure.
• The obtained structural parameters from XAFS were found to be consistent with those from X-ray powder diffraction.
• The study demonstrates the feasibility of using high-pressure XAFS to obtain reliable structural information.

Conclusions:

• High-pressure XAFS is a powerful and reliable technique for characterizing the structure of fullerene superconductors.
• The structural data obtained provides insights into the origin of pressure-induced superconductivity in Cs3C60.
• Detailed procedures for high-pressure XAFS analysis with DAC are presented, aiding future research.