Single crystal growth of the hexagonal manganites R MnO3 (R=rare earth) by the optical floating-zone method

Abstract

We report a study on the crystal growth of the hexagonal manganites R MnO3 (R=Y, Lu, Ho, Er, and Tm) by using an optical floating-zone method. It was found that high-quality single crystals of R=Y, Lu, and Ho could be easily grown with essentially the same conditions as those reported in the literature, that is, with an atmosphere of normal pressure Ar and oxygen mixture and a growth rate of 2–4mm/h. However, these conditions were not feasible for growing good crystals of R=Er and Tm. The chemical analysis indicated that it was due to an off-stoichiometric phenomenon in the formed single crystals. We used an effective and simple way to resolve this problem by adjusting the nominal compositions of the polycrystal feed rods to be 1–2% rare-earth excess. The structures and physical properties were characterized by X-ray diffraction, magnetic susceptibility, specific heat, resistivity, and dielectric constant measurements.