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04:51
Comparison of Two Different Synthesis Methods of Single Crystals of Superconducting Uranium Ditelluride
Published on: July 8, 2021
Bulk superconductivity at 38 K in a molecular system.
Alexey Y Ganin1, Yasuhiro Takabayashi, Yaroslav Z Khimyak
1Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
Nature Materials
|April 22, 2008
Summary
Superconducting cesium fulleride (Cs(3)C(60)) exhibits a record 38 K transition temperature. This molecular superconductor, uniquely adopting the A15 structure, shows pressure-tuned superconductivity linked to electronic correlations.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- Fullerene-based solids, particularly A(3)C(60) compounds, are known molecular superconductors.
- Superconducting transition temperatures (Tc) in these materials correlate with the fullerene C(60) separation, influenced by alkali metal cation size.
- Cesium fulleride (Cs(3)C(60)) is a key material due to the large Cs(+) cation, but its superconducting phase and properties have been poorly characterized.
Purpose of the Study:
- To reproducibly synthesize and characterize superconducting cesium fulleride (Cs(3)C(60)).
- To determine the crystal structure and superconducting properties of Cs(3)C(60).
- To investigate the effect of hydrostatic pressure on the superconductivity of Cs(3)C(60).
Main Methods:
- Solvent-controlled synthesis to isolate superconducting Cs(3)C(60).
- X-ray diffraction and magnetic susceptibility measurements to identify crystal structure and superconductivity.
- Application of hydrostatic pressure to study the tuning of superconducting properties.
Main Results:
- Reproducible isolation of superconducting Cs(3)C(60) with a record transition temperature (Tc) of 38 K, the highest for any molecular material.
- Identification of the superconducting phase as the A15 structure, distinct from the typical face-centered-cubic (f.c.c.) structure found in other A(3)C(60) compounds.
- Demonstration that hydrostatic pressure can tune A15 Cs(3)C(60) from an insulating state to a superconducting state without structural changes, revealing a Tc maximum around 7 kbar.
Conclusions:
- Superconducting Cs(3)C(60) in the A15 structure represents a new class of molecular superconductor with exceptionally high Tc.
- The observed Tc maximum as a function of inter-fullerene separation, tunable by pressure, suggests the critical role of strong electronic correlations near a metal-insulator transition.
- This finding offers new insights into the mechanisms of superconductivity in fullerides and provides a model system for studying correlated electron phenomena.
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