High-frequency dielectric anomalies in a highly frustrated square kagomé lattice nabokoite family compounds ACu7(TeO4)(SO4)5Cl (A = Na, K, Rb, Cs)

• Published in: Journal of magnetism and magnetic materials Vol. 592
• Main Authors: Rebrov, Ya.V., Glazkov, V.N., Murtazoev, A.F., Dolgikh, V.A., Berdonosov, P.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2024
• Subjects: Dielectric properties; Frustrated magnets; Magnetic ordering; Spin-liquid state; Square kagomé lattice; Frustrated magnets; Spin-liquid state; Square kagomé lattice; Magnetic ordering; Dielectric properties
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2024.171786

Nabokoite family compounds ACu7(TeO4)(SO4)5Cl (A = Na, K, Cs, Rb) are candidates for the experimental realization of highly-frustrated 2D square kagomé lattice (SKL). Their magnetic subsystem includes SKL layers decorated by additional copper ions. All members of this family are characterized by quite high Curie–Weiss temperatures (∼ 80–200 K), but magnetic ordering was reported only for Na and K compounds at a much lower temperatures below 4 K. We report here results of the study of high-frequency (∼10 GHz) dielectric properties of this family of compounds. Our study revealed presence of the strong dielectric anomaly both in the real and imaginary parts of high-frequency dielectric permittivity for Na and K compounds approx. 100 and 26 K, correspondingly, presumably related to antiferroelectric ordering. Additionally, much weaker anomalies were observed at approx. 5 K indicating possible interplay of magnetic and lattice degrees of freedom. We discuss possible relation between the structure rearrangements accompanying dielectric anomalies and a delayed magnetic ordering in the nabokoite family compounds. •Nabokoite family compounds – spin liquid candidates on a square kagome lattice.•High-frequency (10 GHz range) dielectric anomalies are found.•High-frequency dielectric anomalies are probably a key to spin liquid freezing.