Single crystal growth by the floating-zone method of a geometrically frustrated pyrochlore antiferromagnet, Tb 2Ti 2O 7

Abstract

Large, high quality, single crystals of Tb 2Ti 2O 7, have been successfully grown by the floating zone method under a controlled atmosphere. Crystals, approximately 3–5 mm in diameter and up to 20 mm in length, were grown from a small seed crystal. Several crystals have been characterised to determine their crystal quality, chemical structure and magnetic properties and these results were compared to those of sintered polycrystalline pellets. These materials were shown to have the face centred cubic structure, Fd–3m, with a room temperature lattice parameter a=10.12(7) Å, when grown in oxygen, and a=10.13(6) Å, when grown in argon. They are currently of interest as they are comprised of antiferromagnetically coupled magnetic moments residing on a network of corner-sharing tetrahedra, a system known to display the effects of geometrical frustration. Magnetic susceptibility measurements, with the applied field parallel to the growth direction were performed on both crystals. Both single crystal and polycrystalline samples showed very similar Curie-Weiss like behaviour down to 5 K, with Curie–Weiss temperatures, θ cw of approximately −19 K.