Phonon Activity and a Possible Lattice Arrangement in the Intermediate Phase of YVO3

TL;DR

This study investigates the lattice dynamics and phase transitions in YVO3, revealing new phonon activity, disorder at low temperatures, and possible incommensurate structures related to magnetic ordering.

Contribution

It identifies new hard phonons and suggests a lattice phase transition with incommensurate features linked to orbital stacking and magnetic order in YVO3.

Findings

Emergence of zone center active phonons below 210 K

Additional disorder observed below 150 K from EXAFS

Evidence of incommensurate-like structures related to magnetic transition

Abstract

We show that in YVO3 new hard phonons gradually become zone center active below ~210 K verifying that a lattice phase transition takes place at about that temperature. The Debye-Waller factor found from EXAFS measurements show an additional disorder below 150K seen as a departure from the thermal behavior. We bring up the similarities of the intermediate phase to known results belonging to incommensurate systems that here we attribute to faulty orbital stacking with possible domain formation set below 116K, the onset temperature of the G-type antiferromagnetism. We found support for this interpretation in the inverted lambda shapes in the measured heat capacity at the phase transitions and in the overall temperature dependence of the reported new hard phonons as compared with those for known incommensurate dielectrics.