Superconductivity at T(c) similar or equal to 40 K in MgB(2) is thought to origin from the strong electron-phonon (el-ph) coupling of the sigma-bands, whereas the residual interband scattering gives rise to the multigap phenomenology. The extremely low charge density of the sigma-bands is reflected in the small Fermi energy E(F)(sigma), a fraction of eV, a common feature which is shared also by cuprates and fullerides. In our contribution we discuss the anomalous effects arising from the small Fermi energy phenomenology, when E(F)(sigma) becomes comparable with the other energy scales of the systems. In particular we analyze the nonadiabatic effects arising from the finite adiabatic ratio omega(ph)/E(F)(sigma); the anharmonic character of the E(2g) phonon mode, which is shown to be related to the smallness of the Fermi energy with respect to the electron-phonon coupling g(E2g):E(F)(sigma) similar to g(E2g); the anomalous effects of disorder when impurity scattering rate gamma(imp) is compared with E(F)(sigma). We discuss also the possibility of an enhancement of the nonadiabatic character due to zero point quantum fluctuations.

Small Fermi energy effects in MgB2 and related compounds / E., Cappelluti; Bachelet, Giovanni Battista; Boeri, Lilia; S., Ciuchi; C., Grimaldi; Pietronero, Luciano; S., Strassler. - In: PHYSICA. C, SUPERCONDUCTIVITY. - ISSN 0921-4534. - STAMPA. - 408:(2004), pp. 332-335. [10.1016/j.physc.2004.02.127]

Small Fermi energy effects in MgB2 and related compounds

BACHELET, Giovanni Battista;BOERI, Lilia;PIETRONERO, Luciano;
2004

Abstract

Superconductivity at T(c) similar or equal to 40 K in MgB(2) is thought to origin from the strong electron-phonon (el-ph) coupling of the sigma-bands, whereas the residual interband scattering gives rise to the multigap phenomenology. The extremely low charge density of the sigma-bands is reflected in the small Fermi energy E(F)(sigma), a fraction of eV, a common feature which is shared also by cuprates and fullerides. In our contribution we discuss the anomalous effects arising from the small Fermi energy phenomenology, when E(F)(sigma) becomes comparable with the other energy scales of the systems. In particular we analyze the nonadiabatic effects arising from the finite adiabatic ratio omega(ph)/E(F)(sigma); the anharmonic character of the E(2g) phonon mode, which is shown to be related to the smallness of the Fermi energy with respect to the electron-phonon coupling g(E2g):E(F)(sigma) similar to g(E2g); the anomalous effects of disorder when impurity scattering rate gamma(imp) is compared with E(F)(sigma). We discuss also the possibility of an enhancement of the nonadiabatic character due to zero point quantum fluctuations.
2004
magnesium diboride, nonadiabaticity, small Fermi energy
01 Pubblicazione su rivista::01a Articolo in rivista
Small Fermi energy effects in MgB2 and related compounds / E., Cappelluti; Bachelet, Giovanni Battista; Boeri, Lilia; S., Ciuchi; C., Grimaldi; Pietronero, Luciano; S., Strassler. - In: PHYSICA. C, SUPERCONDUCTIVITY. - ISSN 0921-4534. - STAMPA. - 408:(2004), pp. 332-335. [10.1016/j.physc.2004.02.127]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1742
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? 1
social impact