## Abstract

We study the energy spectrum of Bi2223 (Bi_{1.6}Pb_{0.4}Sr_{1.8}Ca_{2.2}Cu _{3}O_{x}) at high hydrostatic pressures by Andreev- and tunneling-spectroscopy methods. We determine the gap anisotropy in the basal ab plane and find the following values for the parameters Δ(φ): Δ_{max}=42mV, and Δ_{min}= 19.5 mV (T_{c} = 110 K and dT_{c}/dP = 0.16 K/kbar). We detect an increase in the ratio R = 2Δ_{max}/kT_{c} with pressure P; for Bi2223 cuprate, dR/dP≈0.017 kbar^{-1}. In the phonon-frequency region we detect a "softening," due to pressure, of the high-frequency part of the phonon spectrum corresponding to "breathing" modes of oxygen, as well as other optical modes of Cu-O. The characteristic frequencies of the spectrum for ℏΩ>60 mV are found to decrease, with increasing pressure, at a rate d ln(ℏΩ)/dP≈-6.5±0.5×10^{-3} kbar^{-1}. This result explains the observed increase in the ratio 2Δ/kT_{c}(P) in the model of strong electron-phonon interaction.

Original language | English |
---|---|

Pages (from-to) | 763-770 |

Number of pages | 8 |

Journal | Journal of Experimental and Theoretical Physics |

Volume | 86 |

Issue number | 4 |

DOIs | |

Publication status | Published - 1998 Apr |