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

Abstract

The valence electronic structure of magnetic centers is one of the factors that determines the characteristics of a magnet. It may refer to orbital degeneracy, as for $j_{\text{eff}}=1/2$ Kitaev magnets, or near-degeneracy, e.g. involving the third and fourth shells in cuprate superconductors. Here we explore the inner structure of magnetic moments in group-5 lacunar spinels, fascinating materials featuring multisite magnetic units in the form of tetrahedral tetramers. Our quantum chemical analysis reveals a very colorful landscape, much richer than the single-electron, single-configuration description applied so far to all group-5 Ga$M_4{X}_8$ chalcogenides, and clarifies the basic multiorbital correlations on $M_4$ tetrahedral clusters: while for V strong correlations yield a wave-function that can be well described in terms of four V${}^{4+}$V${}^{3+}$V${}^{3+}$V${}^{3+}$ resonant valence structures, for Nb and Ta a picture of dressed molecular-orbital-like $j_{\text{eff}}=3/2$ entities is more appropriate. These internal degrees of freedom likely shape vibronic couplings, phase transitions, and magneto-electric properties in each of these systems.

6 pages, 3 figures

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Cited by in corpus (5)

• Quasimolecular $J_{\mathrm{tet}}$=3/2 moments in the cluster Mott insulator GaTa${}_4$Se${}_8$
• Cluster rearrangement by chiral charge order in lacunar spinel GaNb${}_4$Se${}_8$
• Jahn-Teller driven quadrupolar ordering and spin-orbital dimer formation in GaNb${}_4$Se${}_8$
• More bridging ligands activate direct exchange: the case of anisotropic Kitaev effective magnetic interactions
• Relevance of on-site and intersite Coulomb interactions in the Kitaev-Heisenberg magnet Na${}_3$Co${}_2$SbO${}_6$