Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-2D honeycomb lattice compound Na2Co2TeO6

Abstract

The crystal structure, magnetic ground state, and the temperature dependent microscopic spin-spin correlations of the frustrated honeycomb lattice antiferromagnet Na2Co2TeO6 have been investigated by powder neutron diffraction. A three dimensional (3D) long-range antiferromagnetic ordering has been found below TN ~ 24.8 K. The magnetic ground state, determined to be zigzag antiferromagnet [k = (1/2 0 0)], occurs due to the competing exchange interactions up to third nearest neighbors within the honeycomb lattice. The exceptional existence of a limited magnetic correlation length along the c axis (perpendicular to the honeycomb layers in the ab planes) has been found within the 3D long-range ordered state, even at 1.8 K, well below TN. The observed limited correlation along the c axis is explained by the disorder distribution of the Na ions within the intermediate layers. The reduced ordered moments mCo(1) = 2.77(3) muB/Co2+ and mCo(2) = 2.45(2) muB/Co2+ at 1.8 K reflect the persistence of spin fluctuations in the ordered state. Above TN, the presence of short-range magnetic correlations, manifested by broad diffuse magnetic peaks, has been found. Reverse Monte Carlo analysis of the experimental diffuse magnetic scattering data reveals that the spin correlations are mainly confined within the 2D honeycomb layers (ab plane) with a correlation length of ~ 12 Å at 25 K. The nature of spin arrangements is found to be similar in both the short-range and long-range ordered magnetic states. This implies that the short-range correlation grows with decreasing temperature and leads to the zigzag AFM ordering at T < TN. The present study provides a comprehensive picture of the magnetic correlations over the temperature range above and below TN and their relation to the crystal structure. The role of intermediate soft Na-layers on the magnetic coupling between honeycomb planes is discussed.

34 Pages, 10 figures

References in corpus (6)

• Magnetic properties of the honeycomb oxide Na${}_2$Co${}_2$TeO${}_6$
• Disordered Ground State and Magnetic Field-Induced Long-Range Order in an S=3/2 Antiferromagnetic Honeycomb Lattice Compound Bi3Mn4O12(NO3)
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• Short-range Magnetic Ordering in the Geometrically Frustrated Layered Compound YBaCo4O7 with an Extended Kagomé Structure
• Effect of electron doping on the magnetic correlations in the bilayered brownmillerite compound Ca_{2.5-x}La_{x}Sr_{0.5}GaMn_{2}O_{8}: a neutron diffraction study

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• Temperature Dependent Na-ion Conduction and its Pathways in the Crystal Structure of the Layered Battery Material Na${}_2$Ni${}_2$TeO${}_6$
• Planar Thermal Hall Effects in Kitaev Spin Liquid Candidate Na2Co2TeO6
• Magnetism of the 2D honeycomb layered Na2Ni2TeO6 compound driven by intermediate Na-layer crystal-structure
• Field and Polarization Dependent Quantum Spin Dynamics in Honeycomb Magnet Na${}_2$Co${}_2$TeO${}_6$: Magnetic Excitations and Continuum
• Two-dimensional short-range spin-spin correlations in the layered spin-3/2 maple leaf lattice antiferromagnet Na2Mn3O7 with crystal stacking disorder
• Spin Waves and Dirac Magnons in a Honeycomb Lattice Zig-zag Antiferromagnet BaNi2(AsO4)2
• Suppression of the antiferromagnetic order by Zn doping in a possible Kitaev material Na${}_2$Co${}_2$TeO${}_6$
• Proposed Negative Thermal Expansion in Honeycomb-Lattice Antiferromagnets