Magnetic Properties of A2Ni2TeO6 (A = K, Li): Zigzag Order in the Honeycomb Layers of Ni2+ Ions Induced by First and Third Nearest-Neighbor Spin Exchanges

Tatyana Vasilchikova; Alexander Vasiliev; Maria Evstigneeva; Vladimir Nalbandyan; Ji-Sun Lee; Hyun-Joo Koo; Myung-Hwan Whangbo

doi:10.3390/ma15072563

Magnetic Properties of A₂Ni₂TeO₆ (A = K, Li): Zigzag Order in the Honeycomb Layers of Ni²⁺ Ions Induced by First and Third Nearest-Neighbor Spin Exchanges

Materials (Basel). 2022 Mar 31;15(7):2563. doi: 10.3390/ma15072563.

Authors

Tatyana Vasilchikova¹, Alexander Vasiliev^{1

2

3}, Maria Evstigneeva⁴, Vladimir Nalbandyan⁴, Ji-Sun Lee⁵, Hyun-Joo Koo⁵, Myung-Hwan Whangbo^{5

6}

Affiliations

¹ Department of Low Temperature Physics and Superconductivity, Lomonosov Moscow State University, Moscow 119991, Russia.
² Quantum Functional Materials Laboratory, National University of Science and Technology "MISiS", Moscow 119049, Russia.
³ Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Ekaterinburg 620002, Russia.
⁴ Faculty of Chemistry, Southern Federal University, Rostov-on-Don 344090, Russia.
⁵ Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Korea.
⁶ Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA.

Abstract

The static and dynamic magnetic properties and the specific heat of K₂Ni₂TeO₆ and Li₂Ni₂TeO₆ were examined and it was found that they undergo a long-range ordering at T_N = 22.8 and 24.4 K, respectively, but exhibit a strong short-range order. At high temperature, the magnetic susceptibilities of K₂Ni₂TeO₆ and Li₂Ni₂TeO₆ are described by a Curie-Weiss law, with Curie-Weiss temperatures Θ of approximately -13 and -20 K, respectively, leading to the effective magnetic moment of about 4.46 ± 0.01 μ_B per formula unit, as expected for Ni²⁺ (S = 1) ions. In the paramagnetic region, the ESR spectra of K₂Ni₂TeO₆ and Li₂Ni₂TeO₆ show a single Lorentzian-shaped line characterized by the isotropic effective g-factor, g = 2.19 ± 0.01. The energy-mapping analysis shows that the honeycomb layers of A₂Ni₂TeO₆ (A = K, Li) and Li₃Ni₂SbO₆ adopt a zigzag order, in which zigzag ferromagnetic chains are antiferromagnetically coupled, because the third nearest-neighbor spin exchanges are strongly antiferromagnetic while the first nearest-neighbor spin exchanges are strongly ferromagnetic, and that adjacent zigzag-ordered honeycomb layers prefer to be ferromagnetically coupled. The short-range order of the zigzag-ordered honeycomb lattices of K₂Ni₂TeO₆ and Li₂Ni₂TeO₆ is equivalent to that of an antiferromagnetic uniform chain, and is related to the short-range order of the ferromagnetic chains along the direction perpendicular to the chains.

Keywords: first principles calculations; honeycomb lattice; long-range order; metaloxides; short-range order.