Magnetic Properties of A 2 Ni 2 TeO 6 (A = K, Li): Zigzag Order in the Honeycomb Layers of Ni 2+ Ions Induced by First and Third Nearest-Neighbor Spin Exchanges

• Published in: Materials Vol. 15; no. 7
• 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: Switzerland 31.03.2022
• Subjects: first principles calculations; honeycomb lattice; long-range order; short-range order; metaloxides
• ISSN: 1996-1944

The static and dynamic magnetic properties and the specific heat of K Ni TeO and Li Ni TeO were examined and it was found that they undergo a long-range ordering at = 22.8 and 24.4 K, respectively, but exhibit a strong short-range order. At high temperature, the magnetic susceptibilities of K Ni TeO and Li Ni TeO 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 per formula unit, as expected for Ni ( = 1) ions. In the paramagnetic region, the ESR spectra of K Ni TeO and Li Ni TeO show a single Lorentzian-shaped line characterized by the isotropic effective -factor, = 2.19 ± 0.01. The energy-mapping analysis shows that the honeycomb layers of A Ni TeO (A = K, Li) and Li Ni SbO 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 K Ni TeO and Li Ni TeO 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.