Chemically tunable quantum magnetism on the anisotropic triangular lattice in rhenium oxyhalides

Le résumé fourni par la source

The spin-1/2 Heisenberg antiferromagnet on an anisotropic triangular lattice (ATL) is an archetypal spin system hosting exotic quantum magnetism and dimensional crossover. However, the progress in experimental research on this field has been limited due to the scarcity of ideal model materials. Here, we show that rhenium oxyhalides A3ReO5X2, where spin-1/2 Re6+ ions form a layered structure of ATLs, allow for flexible chemical substitution in both cation A2+ (A = Ca, Sr, Ba, Pb) and anion X− (X = Cl, Br) sites, leading to seven synthesizable compounds. By combining magnetic susceptibility and high-field magnetization measurements with theoretical calculations using the orthogonalized finite-temperature Lanczos method, we find that the anisotropy $${J}^{{\prime} }/J$$ ranges from 0.25 to 0.45 depending on the chemical composition. Our findings demonstrate that A3ReO5X2 is an excellent platform for realizing diverse effective spin Hamiltonians that differ in the strength of the anisotropy $${J}^{{\prime} }/J$$ as well as the relevance of perturbation terms such as the Dzyaloshinskii-Moriya interaction and interlayer exchange coupling. Frustrated quantum magnets have been studied intensely, owing to their potential of hosting exotic quantum magnetism, however, experimental realisation of model systems, such as the spin-1/2 Heisenberg antiferromagnet on an anisotropic triangular lattice is challenging. Here Gen et al demonstrate that the rhenium oxyhalides, A3ReO5X2, though chemical substitution can span a diverse effective spin Hamiltonians.

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