Quasi-one-dimensional Pb5Re3 O15: A 5d realization of the Heisenberg antiferromagnetic spin-1/2 chain

Quasi-one-dimensional (1D) magnetic compounds connect the exact solutions of low-dimensional magnetic geometries, which promise quantum spin liquid behavior and exotic quasiparticles, with real-world materials, in which competing magnetic interactions affect their implementation in quantum information science. Here, the structural determination and quasi-1D magnetic behavior of a previously unreported compound, Pb5Re3O15, is presented. Like the anisotropic triangular A3ReO5Cl2 (A = Ba, Sr, Ca) materials, Pb5Re3O15 contains [ReO5] square pyramids inserted into anion-centered quasi-two-dimensional layers and hosts spin-1/2 moments on the Re6+ ions. Pb5Re3O15, however, has a more ideal quasi-1D geometry than the A3ReO5Cl2 materials, with larger interchain distances and interlayer spacing. Quasi-1D magnetic behavior in Pb5Re3O15 is confirmed by fitting the temperature-dependent magnetic susceptibility with the Bonner-Fisher model for a spin-1/2 antiferromagnetically coupled chain, yielding an intrachain coupling constant of |J|/kB=54.5K. Pb5Re3O15 is highly insulating at room temperature, and heat capacity data below 10 K reveal a linear-T contribution that suggests the presence of low-temperature spinon excitations. With a lack of three-dimensional ordering down to at least 0.6 K, Pb5Re3O15 is proposed as a model system for studying the quantum magnetism of quasi-1D Heisenberg chains in a real-world 5d1 antiferromagnetic material.