Engineering topics
Ni, Danrui
Publications and source records attributed to Ni, Danrui.
Quasi-one-dimensional Pb 5 Re 3 O 15 : A 5 d 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, Pb 5 Re 3 O 15 , is presented. Like the anisotropic triangular A 3 ReO 5 Cl 2 (A = Ba, Sr, Ca) materials, Pb 5 Re 3 O 15 contains [ReO 5 ] square pyramids inserted into anion-centered quasi-two-dimensional layers and hosts spin-1/2 moments on the Re 6+ ions. Pb 5 Re 3 O 15 , however, has a more ideal quasi-1D geometry than the A 3 ReO 5 Cl 2 materials, with larger interchain distances and interlayer spacing. Quasi-1D magnetic behavior in Pb 5 Re 3 O 15 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|/k B =54.5K. Pb 5 Re 3 O 15 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. Finally, with a lack of three-dimensional ordering down to at least 0.6 K, Pb 5 Re 3 O 15 is proposed as a model system for studying the quantum magnetism of quasi-1D Heisenberg chains in a real-world 5d 1 antiferromagnetic material.
Impersonating a Superconductor: High-Pressure BaCoO 3 , an Insulating Ferromagnet
Not provided.
Superconductivity in electron-doped PbBi 2 Te 4
Single crystals of In-doped PbBi 2 Te 4 are synthesized via a conventional solid-state method. Chemical analysis and Hall measurements indicate that In replaces Pb, introducing n-type carriers, creating Pb 1–x In x Bi 2 Te 4 . A superconducting transition is observed with a maximum transition temperature around 2.06 K for Pb 1–x In x Bi 2 Te 4 . Field-dependent transport measurements reveal type-II superconductivity and yield a maximum upper critical field around 1.55 T. Thermodynamic data indicates bulk superconductivity in the BCS weak-coupling limit. Finally, our findings establish an ambient-pressure superconducting system in the AM 2 X 4 family, and doped PbBi 2 Te 4 as a promising platform for the study of topological superconductivity.