Spin Triplet Ground-State in the Copper Hexamer Compounds A2Cu3O(SO4)3 (A=Na,K)

Abstract

The compounds A2Cu3O(SO4)3 (A=Na,K) are characterized by copper hexamers which are weakly coupled along the b-axis to realize one-dimensional antiferromagnetic chains below TN=3 K, whereas the interchain interactions along the a- and c-axes are negligible. We investigated the energy-level splittings of the copper hexamers by inelastic neutron scattering below and above TN. The eight lowest-lying hexamer states could be unambiguously assigned and parametrized in terms of a Heisenberg exchange Hamiltonian, providing direct experimental evidence for an S=1 triplet ground-state associated with the copper hexamers. Therefore, the compounds A2Cu3O(SO4)3 serve as novel cluster-based spin-1 antiferromagnets to support Haldane's conjecture that a gap appears in the excitation spectrum below TN, which was verified by inelastic neutron scattering.

21 pages, 4 figures, 2 tables

References in corpus (2)

• Cluster-based Haldane state in edge-shared tetrahedral spin-cluster chain: Fedotovite K${}_2$Cu${}_3$O(SO${}_4$)${}_3$
• AgCuVO4: a quasi one-dimensional S = 1/2 chain compound

Cited by in corpus (8)

• Quantum Magnetism in Minerals
• Magnetic hexamers interacting in layers in the (Na,K)${}_2$Cu${}_3$O(SO${}_4{)}_3$ minerals
• Cluster-based Haldane phases, bound magnon crystals and quantum spin liquids of a mixed spin-1 and spin-1/2 Heisenberg octahedral chain
• Spin-Coupling Topology in the Copper Hexamer Compounds A${}_2$Cu${}_3$O(SO${}_4$)${}_3$ (A=Na, K)
• 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
• Imbalanced spin couplings in the copper hexameter compounds A2Cu3O(SO4)3 (A2=Na2, NaK, K2)
• High-field NMR study of the spin correlations in the spin-cluster mineral Na${}_2$Cu${}_3$O(SO${}_4$)${}_3$
• Parity-dependent phase diagrams in spin-cluster two-leg ladders