Dressed jeff-1/2 objects in mixed-valence lacunar spinel molybdates

Abstract

The lacunar-spinel chalcogenides exhibit magnetic centers in the form of transition-metal tetrahedra. On the basis of density-functional computations, the electronic ground state of an Mo413+ tetrahedron has been postulated as single-configuration a12 e4 t25, where a1, e, and t2 are symmetry-adapted linear combinations of single-site Mo t2g atomic orbitals. Here we unveil the many-body tetramer wave-function: we show that sizable correlations yield a weight of only 62% for the a12 e4 t25 configuration. While spin–orbit coupling within the peculiar valence orbital manifold is still effective, the expectation value of the spin–orbit operator and the g factors deviate from figures describing nominal t5jeff = 1/2 moments. As such, our data documents the dressing of a spin–orbit jeff = 1/2 object with intra-tetramer excitations. Our results on the internal degrees of freedom of these magnetic moments provide a solid theoretical starting point in addressing the intriguing phase transitions observed at low temperatures in these materials.

Resonating holes vs molecular spin-orbit coupled states in group-5 lacunar spinels

“…From electronic-structure calculations based on density functional theory (DFT), an valence electron configuration was inferred 8 – 10 . While indications of genuine many-body physics are available from both ab initio quantum chemical investigations 11 – 13 and dynamical mean field theory (DMFT) 14 , an in-depth profile of correlation effects across the 3 d -4 d -5 d lacunar-spinel series is missing, which is the scope of our present quantum chemical study.

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Synthesis and Structural and Magnetic Properties of Polycrystalline GaMo4Se8

“…In the high-temperature phase, the space group of these lacunar spinels, F 43m, is non-centrosymmetric and non-polar. The V 4 and Mo 4 clusters have a T d ( 43m) point symmetry that yields a zero DM interaction in the lowest order [11][12][13]. The JT distortion lowers the T d ( 43m) point symmetry to that of the polar C 3v (3m) point group, allowing the emergence of skyrmions, as in the distorted, polar phase the Dzyaloshinskii-Moriya (DM) interaction is non-vanishing at the lowest order of the moments, i.e., the bilinear, two-spin coupling.…”