Effect of pressure on transition temperature of Rb₃C₆₀ fullerides

Abstract

Electronic structure parameters play a significant role in fullerides leading to a superconducting state. Relevant electronic parameter as renormalized Coulomb repulsive parameter μ* and the attractive electron-phonon coupling strength λ are obtained within the dielectric function formalism for random phase approximation. As a first step, the superconducting transition temperature is deduced within the framework of McMillan approximation and strong coupling results using the widely spread phonon spectrum. In view of the importance of Coulomb screening for doped fullerides, the influence of pressure and volume on T _c are estimated to be within the range of experimental values. The isotope and dopant effects are also discussed. It is noticed that the high-T _c , the huge pressure effect, negative pressure derivative of T _c and positive volume derivative of T _c in alkali intercalated fullerides are dictated by the properties of Coulomb and on-ball-C₆₀ high energy intramolecular modes.

Keywords:

• Fullerenes
• Intramolecular phonons
• Screening
• Pressure effect
• Carbon isotope effect

Acknowledgements

Financial assistance from DRDO Delhi is gratefully acknowledged.

Additional information

Notes on contributors

D. Varshney

Email: [email protected]