Anisotropic hybridization probed by polarization dependent x-ray absorption spectroscopy in VI3 van der Waals Mott ferromagnet

Abstract

Polarization dependent x-ray absorption spectroscopy was used to study the magnetic ground state and the orbital occupation in bulk-phase VI${}_3$ van der Waals crystals below and above the ferromagnetic and structural transitions. X-ray natural linear dichroism and X-ray magnetic circular dichroism spectra acquired at the V $L_{2,3}$ edges are compared against multiplet cluster calculations within the frame of the ligand field theory to quantify the intra-atomic electronic interactions at play and evaluate the effects of symmetry reduction occurring in a trigonally distorted VI${}_6$ unit. We observed a non zero linear dichroism proving the presence of an anisotropic charge density distribution around the V${}^{3+}$ ion due to the unbalanced hybridization between the Vanadium and the ligand states. Such hybridization acts as an effective trigonal crystal field, slightly lifting the degeneracy of the $t_{2g}^2$ ground state. However, the energy splitting associated to the distortion underestimates the experimental band gap, suggesting that the insulating ground state is stabilized by Mott correlation effects rather than via a Jahn-Teller mechanism. Our results clarify the role of the distortion in VI${}_3$ and establish a benchmark for the study of the spectroscopic properties of other van der Waals halides, including emerging 2D materials with mono and few-layers thickness, whose fundamental properties might be altered by reduced dimensions and interface proximity.

References in corpus (13)

• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Strong electronic correlations from Hund's coupling
• Ferromagnetic van der Waals crystal VI3
• VI3 - a new layered ferromagnetic semiconductor
• Bulk properties of van-der-Waals hard ferromagnet VI3
• Magnetic Transition in Monolayer VSe2 via Interface Hybridization
• VI3: a 2D Ising ferromagnet
• Crystal Structures and Phase Transitions of the van-der-Waals Ferromagnet VI3
• Large orbital magnetic moment in VI3
• Proximity-induced ferromagnetism and chemical reactivity in few layers VSe2 heterostructures
• Valence band electronic structure of the van der Waals ferromagnetic insulators: VI${}_3$ and CrI${}_3$
• Magnetic properties of bilayer VI3: Role of trigonal crystal field and electric-field tuning
• Magnetic anisotropy in van-der-Waals ferromagnet VI3

Cited by in corpus (5)

• Symmetry breaking in vanadium trihalides
• Evidence of temperature-dependent interplay between spin and orbital moment in van der Waals ferromagnet VI3
• Electronic Energy Scales of Cr$X_3$ ($X$ = Cl, Br, and I) using High-resolution X-ray Scattering
• Valence Modifications in Hygroscopic VI3 Degraded Crystals via Soft X-Ray Synchrotron Radiation
• Orbital mixing and strong Hund's coupling stabilize spin order in van der Waals ferromagnet CrI3