Bulk magnetization of the heavy rare earth titanate pyrochlores - a series of model frustrated magnets

TLDR

Magnetism in these pyrochlores originates from the rare‑earth ions, while Ti remains non‑magnetic. Magnetization measurements were carried out on R₂Ti₂O₇ (R = Gd, Dy, Ho, Er, Yb) over 1.8–300 K and 0–70 kOe. Low‑field susceptibility analysis shows Gd₂Ti₂O₇ and Er₂Ti₂O₇ exhibit strong antiferromagnetic coupling (–9 K and –22 K, respectively), whereas Ho₂Ti₂O₇, Dy₂Ti₂O₇, and Yb₂Ti₂O₇ display weak ferromagnetic interactions (2 K, 1 K, 1 K) likely dipolar, and high‑field magnetization reveals a pronounced 1,1,1 single‑ion anisotropy, indicating these compounds as potential ferromagnetic spin‑ice realizations.

Abstract

We describe magnetization measurements on the heavy rare earth titanate pyrochlores R2 Ti2 O7 , where R = Gd, Dy, Ho, Er, Yb, in the temperature range 1.8-300 K, and the field range 0-70 000 Oe. In these materials magnetism arises from the rare earth ions, while Ti is non-magnetic. Analysis of the low field susceptibility versus temperature curves shows that Gd2 Ti2 O7has antiferromagnetic coupling ( -9 K), which suggests that it is an example of a frustrated antiferromagnet on the pyrochlore lattice. Er2 Ti2 O7is likewise found to have a large negative Curie-Weiss temperature, -22 K, which we argue is indicative of antiferromagnetic coupling. Ho2 Ti2 O7 , Dy2 Ti2 O7and Yb2 Ti2 O7are found to have weak ferromagnetic coupling ( 2 K, 1 K and 1 K respectively) which may be largely dipolar in origin. Fitting of the high field magnetization versus field curves suggests a strong 1,1,1 single ion anisotropy that identifies these three materials as possible realizations of the ferromagnetic `spin ice' model.