Unique nanowires, new chemical bonding and quasi-1D magnetism in KMn6Bi5

April 5, 2018

In a study published in Journal of the American Chemical Society, researchers showed an incoherent-to-coherent crossover of the intercolumn tunneling of electrons.

(a) Crystal structure of KMn6Bi5 viewed along the column direction [010]. Only Mn–Mn and Bi–Bi bonds are added to exhibit the [Mn6Bi5]− column structure clearly. Direct intercolumn connections via Bi2–Bi2 (3.5687(12) Å) and Bi3–Bi3 (3.6517(13) Å) bonding are present. (b) Side view of the crystal structure perpendicular to the column direction. (c) Mn-cluster column structure with metallic Mn–Mn bonding. (d) Bi nanotube with Bi–Bi bonding in the Bi5 pentagons extended along the column direction. (e) [Mn6Bi5]− nanowires consisting of one Bi nanotube acting as the cladding which is filled with one Mn-cluster core column.

Scientific Achievement

We synthesized a unique antiferromagnetic metal KMn₆Bi₅ that contains naturally formed [Mn₆Bi₅]^- nanowires. The nanowires have a five-fold rotation symmetry with Bi atom sheathing and a vertex-sharing Mn13 icosahedra cluster-based core.

Significance and Impact

KMn₆Bi₅ exhibits 1D-to-3D transitions in electronic transport and magnetism, providing a platform to study the link between magnetism, carrier and dimensionality. The small magnetic moment of Mn makes KMn₆Bi₅ a promising system to search for superconductivity.

Research Details

The structure of KMn₆Bi₅ was solved by single x-ray diffraction and further resolved by high resolution TEM.
Magnetization, and anisotropic resistivity measurements prove an antiferromagnetic order at ~75 K and quasi-one-dimensional nature of magnetism and transport property.

DOI: 10.1021/jacs.8b00465

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