Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 109: Frustrated Magnets - (General) Theory

TT 109.10: Vortrag

Freitag, 16. März 2018, 12:00–12:15, H 3005

Spin model of the Heisenberg antiferromagnet Li₃Ni₂SbO₆: the relevance of third-neighbor exchanges — •Oleg Janson — Institut für Festkörperphysik, TU Wien, Österreich

The quasi-2D S = 1 Heisenberg antiferromagnet Li₃Ni₂SbO₆ exhibits a small Weiss temperature of 8 K and a zigzag magnetic ground state below T_N = 15 K [1,2]. At the same time, the experiments indicate the presence of a short-range magnetic order up to 80 K [2]. The experimental behavior was rationalized in terms of a honeycomb lattice model with inequivalent nearest-neighbor (NN) exchanges [1]: antiferromagnetic J₁ forming dimers and ferromagnetic J₁′ (J₂ in the notation of [1]) forming chains. Puzzled by the drastic dissimilarity of J₁ and J₁′, we performed microscopic magnetic modeling and found that both NN exchanges are ferromagnetic. The antiferromagnetism and magnetic frustration are induced by two sizable third-neighbor exchanges, J₃ and J₃′, that are mediated by the nonmagnetic SbO₆ octahedra in the voids of the honeycomb lattice. The resulting J₁-J₁′-J₃-J₃′ model provides a simple and natural explanation for the observed zigzag state. This work has been supported by the Austrian Science Fund (FWF) through the Lise Meitner programme, project no. M2050.
[1] E. A. Zvereva et al., Phys. Rev. B 92, 144401 (2015).
[2] A. I. Kurbakov et al., Phys. Rev. B 96, 024417 (2017).