The low temperature heat capacity measurements on LSCO samples containing Zn impurities have been performed by means of pulsed differential calorimetry technique. The interpretation of the Zn-concentration dependence of the residual γ-coefficient in the linear temperature part of Cel(T) at T≪Tc is consistent with a model based on the assumption of the d-wave symmetry of the order parameter of these superconducting copper oxides.

The low-temperature heat capacity of cuprates(La2CuO4,La2−xMxCuO4(M = Sr, Ba) and Nd2−xLaxCuO4) is studied in the temperature range 2–45 K by using pulsed differential calorimetry. It is found that the coefficient of the linear term of heat capacity remains unchanged over the entire temperature interval under investigation. The special role of La atoms in the formation of the anomaly in the acoustic region of the phonon spectrum of these compounds near 6 meV is demonstrated. This anomaly is connected with peculiarities in the interaction of these atoms with the environment.

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