Study on the low‐temperature properties of pyrochlores Gd2Hf2O7 and Gd2Zr2O7, using crystal‐field theory

Abstract

The geometrically frustrated pyrochlores Gd2Hf2O7 (GdH) and Gd2Zr2O7 (GdZ) are easy planar anisotropic systems in which considerable single‐ion crystal‐field anisotropies of D3d symmetry are found in the ground multiplet 8S7/2 due to admixture of higher Russell‐Saunders terms. The 8S7/2 splits into 4 doublets with total CF splitting 9.9 K in GdH and 9.4 K in GdZ. The magnetic specific heat Cmag follows a conventional T3 behavior in GdH and an unconventional T4.6 behavior in GdZ down to 0.4 K.