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

• Published in: Materials Vol. 15; no. 7; p. 2563
• Main Authors: Vasilchikova, Tatyana, Vasiliev, Alexander, Evstigneeva, Maria, Nalbandyan, Vladimir, Lee, Ji-Sun, Koo, Hyun-Joo, Whangbo, Myung-Hwan
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 31.03.2022; MDPI
• Subjects: Antiferromagnetism; Chains; Ferromagnetism; first principles calculations; High temperature; honeycomb lattice; Lattices; long-range order; Magnetic moments; Magnetic properties; Magnetism; metaloxides; Potassium; Short range order; Spin dynamics
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15072563

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 TN = 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 μB 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.