Magnetic phase transitions and magnetic entropy in the XY antiferromagnetic pyrochlores (Er1-xYx)(2)Ti2O7

作者：Niven John F; Johnson Michel B; Bourque Alex; Murray Patrick J; James David D; Dabkowska Hanna A; Gaulin Bruce D; White Mary Anne^*

来源：Proceedings of the Royal Society A-Mathematical Physical and Engineering Sciences, 2014, 470(2171): UNSP 20140387.

DOI：10.1098/rspa.2014.0387

• pyrochlore
• antiferromagnetism
• magnetic entropy
• phase transition
• heat capacity

We present the results of experimental determination of the heat capacity of the pyrochlore Er2Ti2O7 as a function of temperature (0.35-300 K) and magnetic field (up to 9 T), and for magnetically diluted solid solutions of the general formula (Er1-xYx)(2)Ti2O7 (x %26lt;= 0.471). On either doping or increase of magnetic field, or both, the Neel temperature first shifts to lower temperature until a critical point above which there is no well-defined transition but a Schottky-like anomaly associated with the splitting of the ground state Kramers doublet. By taking into account details of the lattice contribution to the heat capacity, we accurately isolate the magnetic contribution to the heat capacity and hence to the entropy. For pure Er2Ti2O7 and for (Er1-xYx)(2)Ti2O7, the magnetic entropy as a function of temperature evolves with two plateaus: the first at Rln 2, and the other at Rln 16. When a very high magnetic field is applied, the first plateau is washed out. The influence of dilution at low values is similar to the increase of magnetic field, as we show by examination of the critical temperature versus critical field curve in reduced terms.

• 出版日期2014-11-8