Refined magnetic structure of VI$_3$

Abstract

The van der Waals ferromagnet (FM), VI3, was studied by muon spin relaxation (µ + SR) and first principle calculations based on density functional theory (DFT). Temperature dependent zero field muon spin relaxation (µ + SR) measurements confirm the onset of long range FM order and the time spectra exhibits clear muon spin precession frequencies for T < TC = 50.03(1) K. The calculated internal magnetic fields at the predicted muon sites, based on the established magnetic structure from neutron diffraction, is inconsistent with the measured one. This inconsistency is because of strong incoherent neutron scattering and absorption originating from the elements V and I. Instead, a new and a more accurate magnetic structure is derived based on a combined study using µ + SR and DFT. These results suggest strong contritions from orbital angular momentum, providing experimental evidence for the existence of unquenched orbital angular momentum of V 3+ in VI3. Finally, an unusual form of a short range ordering is present above TC. Its temperature dependence is unlike previously reported cases in other layered compounds and its microscopic origin is discussed.

Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr2O4 revealed with high resolution neutron diffraction and μ+ SR

“…This is due to orbital quenching in a crystal field [36], making this option less probable. Indeed, even though orbital contributions of vanadium in octrahedral environment was in fact recently suggested in VI 3 by µ + SR and XAS [37,38], for NaCr 2 O 4 , an unusual mixed valance electronic state has instead been reported [8]. It was suggested that Na substitution in the solid solution Na x Ca 1−x Cr 2 O 4 does not result in electrons removed from the Cr site, as expected in typical mixed valence compounds.…”