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

• Published in: Nature communications Vol. 14; no. 1; p. 5218
• Main Authors: Petersen, Thorben, Bhattacharyya, Pritam, Rößler, Ulrich K., Hozoi, Liviu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26-08-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/563/758; 639/766/119/995; 639/766/119/997; Chemical analysis; Coupling (molecular); Couplings; Electric properties; Electronic structure; Electrons; Humanities and Social Sciences; Magnetic moments; Magnetic properties; Magnets; multidisciplinary; Phase transitions; Quantum chemistry; Science; Science (multidisciplinary); Single electrons; Spinel; Superconductors
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-40811-y

The valence electronic structure of magnetic centers is one of the factors that determines the characteristics of a magnet. This may refer to orbital degeneracy, as for
j
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
j
eff
 = 3/2 entities is more appropriate. These internal degrees of freedom likely shape vibronic couplings, phase transitions, and the magneto-electric properties in each of these systems.
Dressing is a concept used to describe moderately interacting electrons. Here authors present the notion of dressed spin-orbit 3/2 moments and how this picture breaks down with increasing electronic interactions across group-5 lacunar spinel magnets.