Two inequivalent sublattices and orbital ordering in MnV2O4 studied by 51V NMR

TL;DR

This study uses 51V NMR to investigate orbital ordering in MnV2O4, revealing two distinct V sublattices with stable internal fields that support a specific orbital rotation model.

Contribution

The paper provides detailed NMR evidence confirming the orbital ordering model with two inequivalent V sublattices and orbital rotation in MnV2O4.

Findings

Identification of two V sublattices with distinct hyperfine fields

Internal fields evolve smoothly with external magnetic field

Results support the orbital rotation model in I4_1/a space group

Abstract

We report detailed 51V NMR spectra in a single crystal of MnV2O4. The vanadium spectrum reveals two peaks in the orbitally ordered state, which arise from different internal hyperfine fields at two different V sublattices. These internal fields evolve smoothly with externally applied field, and show no change in structure that would suggest a change of the orbital ordering. The result is consistent with the orbital ordering model recently proposed by Sarkar et al. [Phys. Rev. Lett. 102, 216405 (2009)] in which the same orbital that is a mixture of t_2g orbitals rotates by about 45$^\circ$ alternately within and between orbital chains in the I4_1/a tetragonal space group.