Heat capacity of La1-xSrxMnO3 single crystals in different magnetic states

The heat capacity of three single-crystal samples of La1-xSrxMnO3 (x = 0, 0 .2, and 0.3) is measured in the temperature range 4-400 K. It is found that the heat capacity undergoes abrupt changes due to the transitions from the antiferromagnetic phase to the paramagnetic phase (x = 0) and from the fer romagnetic phase to the paramagnetic phase (x = 0.2 and 0.3). The phonon co ntribution to the heat capacity and the Debye characteristic temperatures f or the La0.7Sr0.3MnO3 sample are determined over a wide range of temperatur es. The electronic density of states at the Fermi level is evaluated. It is demonstrated that an increase in the strontium concentration x brings abou t an increase in the electronic density of states at the Fermi level. The c ontributions of spin waves to the heat capacity and the entropy are estimat ed under the assumption that the phonon spectrum remains unchanged upon dop ing with Sr. (C) 2000 MAIK "Nauka/Interperiodica".