ANi(5)Bi(5.6+6 )(A = K, Rb, and Cs): Quasi-One-Dimensional Metals Featuring [Ni5Bi(5.6+6)]- Double-Walled Column with Strong Diamagnetism

A new series of compounds, ANi5Bi5.6+delta (where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni5Bi5.6+delta]- 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 AMn6Bi5 (where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi5Bi5.6+delta. First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi5Bi5.6+delta, which may explain the emergence of diamagnetism. ANi5Bi5.6+delta, as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.