The Synthesis of a Quasi-One-Dimensional Iron-Based Telluride with Antiferromagnetic Chains and a Spin Glass State.

The report on the superconductivity of the two-legged spin ladders BaFe ₂ S ₃ and BaFe ₂ Se ₃ has established 123-type iron chalcogenides as a novel subgroup in the iron-based superconductor family and has stimulated the continuous exploration of other iron-based materials with new structures and potentially novel properties. In this paper, we report the systematic study of a new quasi-one-dimensional (1D) iron-based compound, Ba ₉ Fe ₃ Te ₁₅ , including its synthesis and magnetic properties. The high-pressure synthesized Ba ₉ Fe ₃ Te ₁₅ crystallized in a hexagonal structure that mainly consisted of face-sharing FeTe ₆ octahedral chains running along the c axis, with a lattice constant of a = 10.23668 Å; this led to weak interchain coupling and an enhanced one-dimensionality. The systematic static and dynamic magnetic properties were comprehensively studied experimentally. The dc magnetic susceptibility showed typical 1D antiferromagnetic characteristics, with a T _max at 190 K followed by a spin glass (SG) state with freezing at T _f ≈ 6.0 K, which were also unambiguously proved by ac susceptibility measurements. Additionally, X-ray magnetic circular dichroism (XMCD) experiments revealed an unexpected orbital moment for Fe ²⁺ , i.e., 0.84 μ _B per Fe in Ba ₉ Fe ₃ Te ₁₅ . The transport property is electrically insulating, with a thermal activation gap of 0.32 eV. These features mark Ba ₉ Fe ₃ Te ₁₅ as an alternative type of iron-based compound, providing a diverse candidate for high-pressure studies in order to pursue some emerging physics.