A comparative Raman study between YbVO3 and YVO3

An orbital ordering effect is observed in YbVO3 around 170 K while the crystal structure is orthorhombic (space group pnma). A monoclinic transition has been reported below TN = 104 K, while according to recent specific heat measurements, it occurs at 170 K. The crystal structure of YVO3 at 300 K is also orthorhombic. It becomes monoclinic at Tc = 200 K and back orthorhombic at T = 77 K. Spins order into the C-type antiferromagnetic structure below TN1 = 116 K and the order changes into the G-type antiferromagnetic
structure below TN2 = 77 K. Controversial interpretations of YVO3 Raman active excitations have been reported. For instance the 489 and 679 cm-1 excitations have been assigned either to phonons or orbitons in two recent studies. In this communication we present a micro-Raman study of YbVO3 and YVO3 Raman active excitations as a function of temperature in order to trace the multiple phase transitions. Also by comparing the two single crystals spectra and previous studies in rare-earth manganites, high energy Raman active excitations are tentatively assigned.