Effects of Non-Stoichiometry on the Ground State of the Frustrated System Li0.8Ni0.6Sb0.4O2

Evgeniya Vavilova; Timur Salikhov; Margarita Iakovleva; Tatyana Vasilchikova; Elena Zvereva; Igor Shukaev; Vladimir Nalbandyan; Alexander Vasiliev

doi:10.3390/ma14226785

Effects of Non-Stoichiometry on the Ground State of the Frustrated System Li_0.8Ni_0.6Sb_0.4O₂

Materials (Basel). 2021 Nov 10;14(22):6785. doi: 10.3390/ma14226785.

Authors

Evgeniya Vavilova¹, Timur Salikhov¹, Margarita Iakovleva^{1

2}, Tatyana Vasilchikova³, Elena Zvereva³, Igor Shukaev⁴, Vladimir Nalbandyan⁴, Alexander Vasiliev^{3

5}

Affiliations

¹ Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of RAS, 420029 Kazan, Russia.
² 3rd Physics Institute, University of Stuttgart, 70569 Stuttgart, Germany.
³ Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia.
⁴ Faculty of Chemistry, Southern Federal University, 344090 Rostov-on-Don, Russia.
⁵ Quantum Functional Materials Laboratory, National University of Science and Technology "MISiS", 119049 Moscow, Russia.

Abstract

The non-stoichiometric system Li_0.8Ni_0.6Sb_0.4O₂ is a Li-deficient derivative of the zigzag honeycomb antiferromagnet Li₃Ni₂SbO₆. Structural and magnetic properties of Li_0.8Ni_0.6Sb_0.4O₂ were studied by means of X-ray diffraction, magnetic susceptibility, specific heat, and nuclear magnetic resonance measurements. Powder X-ray diffraction data shows the formation of a new phase, which is Sb-enriched and Li-deficient with respect to the structurally honeycomb-ordered Li₃Ni₂SbO₆. This structural modification manifests in a drastic change of the magnetic properties in comparison to the stoichiometric partner. Bulk static (dc) magnetic susceptibility measurements show an overall antiferromagnetic interaction (Θ = -4 K) between Ni²⁺ spins (S = 1), while dynamic (ac) susceptibility reveals a transition into a spin glass state at a freezing temperature T_SG ~ 8 K. These results were supported by the absence of the λ-anomaly in the specific heat C_p(T) down to 2 K. Moreover, combination of the bulk static susceptibility, heat capacity and ⁷Li NMR studies indicates a complicated temperature transformation of the magnetic system. We observe a development of a cluster spin glass, where the Ising-like Ni²⁺ magnetic moments demonstrate a 2D correlated slow short-range dynamics already at 12 K, whereas the formation of 3D short range static ordered clusters occurs far below the spin-glass freezing temperature at T ~ 4 K as it can be seen from the ⁷Li NMR spectrum.

Keywords: honeycomb lattice; magnetic frustration; metal oxides.