Specific heat of hexagonal Yb1−xSrxMnO3

Abstract

We have studied influence of the strontium doping in polycrystalline YbMnO3, that is, Yb1−xSrxMnO3 (x = 0.05 and 0.1) multiferroic ceramics, by investigating their magnetic and thermodynamic properties. X-ray powder diffraction measurements on these compounds demonstrated that both samples crystallize in the hexagonal phase with P63cm space group. Antiferromagnetic ordering temperature, as determined by heat capacity measurements, is found to decrease from 86 K (at x = 0.05) to 83 K (at x = 0.1). The compound shows ferromagnetic (FM) ordering at ~4 K due to ordering of the moments of Yb3+ ions in crystallographic site 2a. A Schottky anomaly is observed at around 7 K due to moments of the Yb3+ at the 4b sites as a result of the molecular field present due to Mn3+ ions. Effective molecular fields are estimated to be H mf = 4.6 and 3.0 T for x = 0.05 and x = 0.1, respectively, from the analysis of the observed Schottky anomaly. The magnetic entropy changes (ΔS mag) obtained for samples with x = 0.05 and 0.1 are found to be ~2.24 and ~2.1 J mol−1 K−1, respectively. The relative cooling power is found to be 29 and 28 J mol−1 for a field change of 100 kOe for x = 0.05 and 0.1, respectively.