ANi 5 Bi 5.6+δ (A = K, Rb, and Cs): Quasi-One-Dimensional Metals Featuring [Ni 5 Bi 5.6+δ ] - Double-Walled Column with Strong Diamagnetism.

A new series of compounds, ANi 5 Bi 5.6+δ (where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni 5 Bi 5.6+δ ] - double-walled column and a coaxial inner one-dimensional Bi atomic chain. The columns are linked to each other by intercolumn Bi-Bi bonds and separated by an A + cation. Typical metallic behaviors with strong correlation of itinerant electrons and the Sommerfeld coefficient enhanced with the increasing cationic radius were experimentally observed and supported by first-principles calculations. Compared to AMn 6 Bi 5 (where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi 5 Bi 5.6+δ . First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi 5 Bi 5.6+δ , which may explain the emergence of diamagnetism. ANi 5 Bi 5.6+δ , as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.