A concrete realization of specific heat-phonon spectrum inversion for YBCO

In this Letter, a phonon spectrum of YBCO is obtained fr om its experimenta l specific heat data by an exact inversion formula with eliminating diverge nce parameter [Dai Xianxi, Xu Xinwen and Dai Jiqiong, proceedings of Beijin g International Conference on High T-c Superconductivity, Sept. 4-8 Beijing , China, (1989) 521], [Dai Xianxi, Xu Xinwen and Dai Jiqiong, Phys. Lett. A 147 (1990) 445]. The results are comparable to that from neutron inelastic scattering. Some key points of specific heat-phonon spectrum inversion (SP I) theory as well as a method of asymptotic behavior control are discussed. An improved unique existence theorem is presented. A universal function se t for the numerical calculation in SPI is obtained, which will make the inv ersion method applicable and convenient in practice. This is the first time to realize the specific heat-phonon spectrum inversion in a concrete syste m. (C) 1999 Elsevier Science B.V. All rights reserved.