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Magnetic and structural dimer networks in layered K2Ni(MoO4)2

Murugan, G. S.; Ramesh Babu, K.; Sankar, R.; Chen, W. T.; Panneer Muthuselvam, I.; Chattopadhyay, S.; Choi, K.-Y.

The magnetic and thermodynamic properties of layered single-crystal K2Ni(MoO4)2 having both structural and magnetic dimers have been investigated. The crystal structure of K2Ni(MoO4)2 is composed of edge-sharing NiO6-octahedral pairs bridged by the MoO4 2− polyatomic ion groups in a plane, and the K+ ions sit in the van der Waals gap between the layers. The temperature dependence of magnetic susceptibility shows a spin-singlet ground state with an activation gap of Δ/kB ≈ 38 K. A high-field magnetization study at T = 1.5 K exhibits a half-magnetization plateau at μ0H ∼ 25 T, corresponding to a level crossing of the singlet ground state with the lowest triplet state. Further, we have performed density functional theory calculations to determine magnetic exchange interactions. The nearest-neighbor coupling constant J1 ∼ 10 K between the Ni spins turns out to be an order of magnitude larger than all interdimer couplings. Our experimental and theoretical results suggest that K2Ni(MoO4)2 constitutes a nearly isolated two-dimensional S = 1 dimer model.

Permalink: https://www.hzdr.de/publications/Publ-32341
Publ.-Id: 32341