Magnetic structure, excitations and short-range order in honeycomb Na2Ni2TeO6
- Univ. of Texas at El Paso, TX (United States)
- Univ. of Missouri, Columbia, MO (United States)
- Polish Academy of Sciences (PAS), Krakow (Poland)
- Univ. of Texas at El Paso, TX (United States); National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
Na2Ni2TeO6 has a layered hexagonal structure with a honeycomb lattice constituted by Ni2+ and a chiral charge distribution of Na+ that resides between the Ni layers. In the present work, the antiferromagnetic transition temperature of Na2Ni2TeO6 is confirmed at TN˜ 27 K, and further, it is found to be robust up to 8 T magnetic field and 1.2 GPa external pressure; and, without any frequency-dependence. Slight deviations from nominal Na-content (up to 5%) does not seem to influence the magnetic transition temperature, TN. Isothermal magnetization curves remain almost linear up to 13 T. Our analysis of neutron diffraction data shows that the magnetic structure of Na2Ni2TeO6 is faithfully described by a model consisting of two phases described by the commensurate wave vectors vec kc, (0.5 0 0) and (0.5 0 0.5), with an additional short-range order component incorporated in to the latter phase. Consequently, a zig-zag long-range ordered magnetic phase of Ni2+ results in the compound, mixed with a short-range ordered phase, which is supported by our specific heat data. Theoretical computations based on density functional theory (DFT) predict predominantly in-plane magnetic exchange interactions that conform to a J1-J2-J3 model with a strong J3 term. The computationally predicted parameters lead to a reliable estimate for TN and the experimentally observed zig-zag magnetic structure. A spin wave excitation in Na2Ni2TeO6 at E ˜ 5 meV at T = 5 K is mapped out through inelastic neutron scattering experiments, which is reproduced by linear spin wave theory calculations using the J values from our computations. Our specific heat data and inelastic neutron scattering data strongly indicate the presence of short-range spin correlations, at T > TN, stemming from incipient antiferromagnetic clusters.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Office
- Grant/Contract Number:
- AC36-08GO28308; AC07-05ID14517
- OSTI ID:
- 1808682
- Alternate ID(s):
- OSTI ID: 1811703
- Report Number(s):
- NREL/JA-5900-76750; INL/JOU-20-58007-Rev000; MainId:9411; UUID:974882ca-ff96-4a62-bda0-6a95bb47fa0c; MainAdminID:25802
- Journal Information:
- Journal of Physics. Condensed Matter, Vol. 33, Issue 37; ISSN 0953-8984
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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