Phonon, magnon and electron contributions to low temperature specific heat in metallic state of La0·85Sr0·15MnO3 and Er0·8 Y 0·2MnO3 manganites

The reported specific heat C (T) data of the perovskite manganites, La0·85Sr0·15MnO3 and Er0·8 Y 0·2MnO3, is theoretically investigated in the temperature domain 3 ≤ T ≤ 50 K. Calculations of C (T) have been made within the three-component scheme: one is the fermion and the others are boson (phonon and magnon) contributions. Lattice specific heat is well estimated from the Debye temperature for La0·85Sr0·15MnO3and Er0·8 Y 0·2MnO3 manganites. Fermion component as the electronic specific heat coefficient is deduced using the band structure calculations. Later on, following double-exchange mechanism the role of magnon is assessed towards specific heat and found that at much low temperature, specific heat shows almost T3/2 dependence on the temperature. The present investigation allows us to believe that electron correlations are essential to enhance the density of states over simple Fermi-liquid approximation in the metallic phase of both the manganite systems. The present numerical analysis of specific heat shows similar results as those revealed from experiments.