Crystal growth, characterization, and phase transition of PbCuTe2O6

Single crystals of the three dimensional frustrated magnet and spin liquid candidate PbCuTe2O6 were grown using both the traveling solvent floating zone and the top seeded solution growth TSSG techniques. The growth conditions were optimized by investigating the thermal properties. The quality of the crystals was checked by polarized optical microscopy, x ray Laue, and x ray powder diffraction and compared to the polycrystalline samples. Excellent quality crystals were obtained by the TSSG method. Magnetic measurements of these crystals revealed a small anisotropy for different crystallographic directions in comparison with the previously reported data. The heat capacity of both single crystal and powder samples reveal a transition anomaly around 1 K. Curiously the position and magnitude of the transition are strongly dependent on the crystallite size, and it is almost absent for the smallest crystallites. A structural transition is suggested which accompanies the reported ferroelectric transition, and a scenario whereby it becomes energetically unfavorable in small crystallites is propose