Magnetic phase transitions and magnetic entropy in theXYantiferromagnetic pyrochlores (Er1-xYx)2Ti2O7.
We present the results of experimental determination of the heat capacity of the pyrochlore Er2Ti2O7as 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)2Ti2O7(x≤0.471). On either doping or increase of magnetic field, or both, the Néel 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 Er2Ti2O7and for (Er1-xYx)2Ti2O7, the magnetic entropy as a function of temperature evolves with two plateaus: the first at [Formula: see text], and the other at [Formula: see text]. 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.
Department of Physics and Atmospheric Science , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
John F
JF
Niven
Institute for Research in Materials , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
Michel B
MB
Johnson
Department of Chemistry , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
Alex
A
Bourque
Department of Chemistry , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
Patrick J
PJ
Murray
Department of Chemistry , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
David D
DD
James
Brockhouse Institute for Materials Research , McMaster University , Hamilton, Ontario, L8S 4M1, Canada.
Hanna A
HA
Da̧bkowska
Brockhouse Institute for Materials Research , McMaster University , Hamilton, Ontario, L8S 4M1, Canada ; Department of Physics and Astronomy , McMaster University , Hamilton, Ontario, L8S 4M1, Canada.
Bruce D
BD
Gaulin
Department of Physics and Atmospheric Science , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada ; Institute for Research in Materials , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada ; Department of Chemistry , Dalhousie University , Halifax, Nova Scotia, B3H 4R2, Canada.
Mary Anne
MA
White
antiferromagnetism; heat capacity; magnetic entropy; phase transition; pyrochlore