2025/12/10 by Jing, Jingjing, Eich, Andreas, Liu, Yiqiu +9
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2512.09584
The square-kagome lattice, composed of two-dimensional corner-sharing triangles, provides a novel platform for studying frustrated magnetism. However, material realizations of the square-kagome lattice remain scarce. Here, we report the single-crystal growth, structural characterization, magnetic and electric properties of KCu7TeO4(SO4)5Cl, a nabokoite-type compound featuring a distorted and decorated square-kagome lattice. Weak anomalies near 4 K are observed in both magnetization and specific heat, indicating the onset of a magnetic transition.The formation of a long-range antiferromagnetic state below 4.5 K is further confirmed by 35Cl nuclear magnetic resonance (NMR) measurements. Magnetic susceptibility data reveal nearly isotropic Curie-Weiss temperatures (∼-145 K) and g-factors (∼2.4) for both in-plane and out-of-plane magnetic fields. Moreover, we observe two successive ferroelectric transitions at TFE1∼30 K and TFE2∼27 K, driven by inversion-symmetry breaking, most likely associated with distortions in the Cu2O4Cl1 pyramids and the adjacent SO4 tetrahedra. These results suggest that a three-dimensional model incorporating interlayer couplings via decorating sites is essential for capturing the magnetic and electric behaviors in KCu7TeO4(SO4)5Cl.