ANALYSIS OF EXPERIMENTAL HEAT-CAPACITY OF HOBA2CU3O7-DELTA - ELECTRONHEAT-CAPACITY, CHARACTERISTICS OF PHONON-SPECTRUM

The electron component gamma T is separated from the experimental heat capacity of HoBa2Cu3O7-delta in the normal state region (above T-C). A special technique was used to separate the heat capacity into phonon and electron components. It is based on the representation of the lat tice heat capacity by means of a finite number of moments Theta(i) of the phonon density of states. In addition to gamma, the values of the second moment Theta(2), the fourth moment Theta(4) and the effective m oment Theta characterizing the upper boundary of the phonon density o f states are obtained. The general softening of the phonon spectrum of HoBCO as compared to the phonon spectrum of YBCO is due to substituti on of the light ion Y by the heavy ion Ho. This softening of the phono n density of states opens the possibility for HoBa2Cu3O7-delta to sepa rate both the electron heat capacity ill the region of superconducting transition and the heat capacity jump Delta C.