Laser-diode-heated floating-zone crystal growth of ErVO3

Abstract

The laser-diode-heated floating-zone (LDFZ) is a new variant of the floating-zone (FZ) technique where the molten-zone is established using a set of horizontal laser beams. Unlike a conventional mirror-type FZ, the non-divergent property of the laser beam in LDFZ allows for the growth of high melting temperature refractory materials comprising volatile components. The compound ErVO3 not only has a high melting temperature (∼2100 °C), it also contains volatile V2O3 as one of the components. We show here that large (cm-size) and high-quality crystals of ErVO3 can be obtained with relative ease using the LDFZ technique. In contrast, using the conventional FZ technique, an excessive evaporation of V2O3 from the molten-zone and the feed-rod led to discontinuation of growth within a short time; and the resulting boule, about 2 cm long, was essentially polycrystalline with tiny (less than 1 mm in size) crystals embedded in it. The high-quality of the LDFZ-grown crystal boule is inferred using optical and electron microscopies, Laue backscattering and neutron diffraction techniques. Magnetic susceptibility, neutron diffraction and specific heat measurements on the grown crystal confirmed the presence of orbital ordering at TOO = 195 K, V3+ spin ordering at TM1 = 110 K, simultaneous spin and orbital ordering at TM2 = 58 K, and the long-range ordering of the Er moments near 2.5 K. Our work establishes a relatively straightforward method of growing large crystals of the RVO3 family of compounds. The method can be extended to other high melting temperature refractory materials with volatile components.