Magnetic hexamers interacting in layers in the (Na,K)${}_2$Cu${}_3$O(SO${}_4{)}_3$ minerals

Abstract

Magnetic properties and underlying magnetic models of the synthetic A${}_2$Cu${}_3$O(SO${}_4{)}_3$ fedotovite (A = K) and puninite (A = Na) minerals, as well as the mixed euchlorine-type NaKCu${}_3$O(SO${}_4{)}_3$ are reported. We show that all these compounds contain magnetic Cu${}_6$ hexamer units, which at temperatures below about 100 K act as single spin-1 entities. Weak interactions between these magnetic molecules lead to long-range order below $T_N$ = 3.4 K (A = Na), 4.7 K (A = NaK), and about 3.0 K (A = K). The formation of the magnetic order is elucidated by ab initio calculations that reveal two-dimensional inter-hexamer interactions within crystallographic $bc$ planes. This model indicates the presence of a weakly distorted square lattice of $S=1$ magnetic ions and challenges the earlier description of the A${}_2$Cu${}_3$O(SO${}_4{)}_3$ minerals in terms of Haldane spin chains.

published version, re-worked compared to the initial submission

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• Generalized Directed Loop Method for Quantum Monte Carlo Simulations
• Electric field-induced Skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3
• Observation of two independent skyrmion phases in a chiral magnetic material
• The quantum origins of skyrmions and half-skyrmions in Cu2OSeO3
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• Quasi-two-dimensional $S=1/2$ magnetism of Cu[C${}_6$H${}_2$(COO)${}_4$][C${}_2$H${}_5$NH${}_3$]${}_2$
• Spin excitations in the skymion host Cu2OSeO3
• Spin-Coupling Topology in the Copper Hexamer Compounds A${}_2$Cu${}_3$O(SO${}_4$)${}_3$ (A=Na, K)

Cited by in corpus (6)

• Low-dimensional magnetism of BaCuTe${}_2$O${}_6$
• Imbalanced spin couplings in the copper hexameter compounds A2Cu3O(SO4)3 (A2=Na2, NaK, K2)
• Long range 3D magnetic structures of the spin $S$=1 hexamer cluster fedotovite-like A${}_2$Cu${}_3$O(SO${}_4$)${}_3$ (A${}_2$=K${}_2$, NaK, Na${}_2$): a neutron diffraction study
• High-field NMR study of the spin correlations in the spin-cluster mineral Na${}_2$Cu${}_3$O(SO${}_4$)${}_3$
• Pressure-tuned spin chains in brochantite, Cu${}_4$SO${}_4$(OH)${}_6$
• Geometrical frustration and incommensurate magnetic order in Na${}_3$RuO${}_4$ with two triangular motifs