Structure and orbital ordering of ultrathin LaVO₃probed by atomic resolution electron microscopy and Raman spectroscopy

Abstract

Orbital ordering has been less investigated in epitaxial thin films, due to the difficulty to evidence directly the occurrence of this phenomenon in thin film samples. Atomic resolution electron microscopy enabled us to observe the structural details of the ultrathin LaVO3 films. The transition to orbital ordering of epitaxial layers as thin as ≈4 nm was probed by temperature‐dependent Raman scattering spectroscopy of multilayer samples. From the occurrence and temperature dependence of the 700 cm–1 Raman active mode it can be inferred that the structural phase transition associated with orbital ordering takes place in ultrathin LaVO3 films at about 130 K.

Fingerprints of spin-orbital polarons and of their disorder in the photoemission spectra of doped Mott insulators with orbital degeneracy

“…,Lu, which reveal temperature-induced magnetization reversals [41] as a result of the coupling of spin and orbital degrees of freedom of the t 2g valence electrons [42][43][44][45][46][47]. This class of compounds has interesting phase diagrams with two complementary spinorbital ordered phases and a pure orbital-ordered phase [48][49][50][51][52][53][54]. Remarkably, the C-type spin and G-type orbital ordered phase in La 1−x Sr x VO 3 , Pr 1−x Ca x VO 3 and Y 1−x Ca x VO 3 is robust up to high-doping concentrations and also the metalinsulator transition takes place only at quite substantial doping [55][56][57][58].…”

Coupling of electronic and structural degrees of freedom in vanadate superlattices

“…Experimentally, this was examined in high-pressure studies, which showed that the ground state of RVO 3 can be altered under sufficient pressure [43][44][45]. This lattice coupling was also inspected in thin films of LaVO 3 [46][47][48][49] and PrVO 3 [50,51], where biaxial epitaxial strain was utilized to modify their ordering temperatures.…”