Thermodynamic properties of multiferroic Mg doped YbMnO < inf > 3 < /inf >

Abstract

Calorimetric studies of polycrystalline samples Yb1-xMgxMnO3 with x = 0.0 and 0.05 are reported. It is revealed that the Mg doping raises the antiferromagnetic ordering temperature, TN, from 83 K for x = 0.0 to 86 K for x = 0.05. A ferromagnetic ordering is also observed around 3 K. The broad feature in the specific heat data just above ferromagnetic ordering, is attributed to the Schottky anomaly. The estimated effective molecular fields from the Schottky analysis are Hmf = 3.0 and 3.5 T for YbMnO3 and Yb0.95Mg0.05MnO3, respectively. High temperature shift of Schottky anomaly with Mg doping indicates increase in effective molecular field of Mn at the Yb 4b site. The data supports that the idea that although molecular field is mainly responsible for the Schottky anomaly in Yb1-xMgxMnO3 and Mn3+ spin ordering also affects it. Magnetic part of the specific heat is obtained by subtracting the lattice contribution estimated using two Debye temperatures. The magnetic entropy change (ΔSmag) for pure and doped samples are 2.0 J mol-1 K-1 and 2.1 J mol-1 K-1 respectively, while the relative cooling power (RCP) calculate 26.1 J/mol, 27.2 J/mol for a field change of 10 T.