Collinear and noncollinear antiferromagnetic ordering in a highly frustrated decorated square kagomé lattice antiferromagnets of the nabokoite family

@misc{glazkov2026collinear,
  title = {{Collinear and noncollinear antiferromagnetic ordering in a highly frustrated decorated square kagomé lattice antiferromagnets of the nabokoite family}},
  author = {V. N. Glazkov and Ya V. Rebrov and M. A. Dubovitskii and M. M. Markina and K. V. Zakharov and A. F. Murtazoev and P. S. Berdonosov and A. N. Vasiliev},
  howpublished = {arXiv},
  year = {2026},
  month = aug,
  doi = {10.48550/arxiv.2608.29330},
  eprint = {2608.29330},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2608.29330},
}

TY  - UNPB
TI  - Collinear and noncollinear antiferromagnetic ordering in a highly frustrated decorated square kagomé lattice antiferromagnets of the nabokoite family
AU  - V. N. Glazkov
AU  - Ya V. Rebrov
AU  - M. A. Dubovitskii
AU  - M. M. Markina
AU  - K. V. Zakharov
AU  - A. F. Murtazoev
AU  - P. S. Berdonosov
AU  - A. N. Vasiliev
PY  - 2026
DA  - 2026/08/29
PB  - arXiv
DO  - 10.48550/arxiv.2608.29330
UR  - https://arxiv.org/abs/2608.29330
AB  - Nabokoite family compounds ACu_7(TeO_4)(SO4)_5X (A=Na, K, Rb, Cs; X=Cl, Br) host frustrated 2D square kagom'{e} lattice layers decorated by additional inter-layer magnetic ions. We study magnetic order in nabokoites with multi-frequency electron spin resonance spectroscopy and thermodynamic measurement (specific heat, magnetization and dielectric permittivity). Our study reveals that the choice of the low-temperature ground state is qualitatively different in light-alkali-ion (K, Na) and heavy-alkali-ion (Rb, Cs) compounds. Heavy-alkali-ion nabokoites order in conventional collinear antiferromagnetic pattern with easy-axis anisotropy. The parameters of the ordered antiferromagnetic state are very close for all heavy-alkali-ion subfamily. Light-alkali-ion members of nabokoite family demonstrate much more complicated route to the ordered state: firstly, a ferroelectric transition at 25-90K lifts the frustration and thus pre-cooks the low-temperature ordering; secondly, an unusual noncollinear magnetic order develops via two-step phase transition with first transition temperature T_c1≃ 5−6K and the second transition at T_c2≃ 3−4K. Noncollinear order is evidenced by observation of characteristic non-Larmor antiferromagnetic resonance mode. Spin dynamics of light-alkali-ion nabokoites is characterized by three zero-field magnon gaps and two spin-reorientation fields, the values of magnon gaps and critical fields are quite different for different compounds. The finite-size cluster modeling of pyramidal structural block of nabokoite structure combined suggests that the critical closeness of the nabokoite exchange coupling parameters to the border-line between the different quantum ground state of pyramidal building block of nabokoite structure could be the clue to the choice of qualitatively different ordered state in light- and heavy-alkali-ion nabokoites.
ER  -