Orbital Ordering in ferromagnetic Lu2V2O7

TL;DR

This study reveals the orbital ordering in ferromagnetic Lu2V2O7 using polarized neutron diffraction, identifying a specific orbital pattern and discussing its stability with a Hubbard model.

Contribution

First direct observation of orbital ordering in Lu2V2O7 and explanation of the pattern using wave functions and a Hubbard Hamiltonian.

Findings

Orbital ordering pattern identified as a combination of |yz>, |zx>, |xy> orbitals.

The orbital pattern is proportional to (x + y + z)^2 - r^2.

Discussion of the stability of ferromagnetism using a Hubbard model.

Abstract

We have observed the orbital ordering in the ferromagnetic Mott-insulator Lu2V2O7 by the polarized neutron diffraction technique. The orbital ordering pattern determined from the observed magnetic form factors can be explained in terms of a linear combination of wave functions |yz>, |zx> and |xy>; |0> = (1/3)^(1/2) |xy> + (1/3)^(1/2)|yz> + (1/3)^(1/2) |zx> which is proportional to |(x + y + z)^2 - r^2>; where each orbital is extended toward the center-of-mass of the V tetrahedron. We discuss the stability of the ferromagnetic Lu2V2O7, using a Hubbard Hamiltonian with these three orbitals.