  Two-dimensional (2D) metal-diboride ZrB2 monolayers was predicted
theoretically as a stable new electronic material [A. Lopez-Bezanilla, Phys.
Rev. Mater., 2018, 2, 011002 (R)]. Here, we investigate its electronic
transport properties along the zigzag (z-ZrB2) and armchair (a-ZrB2)
directions, using the density functional theory and non-equilibrium Green's
function methods. Under low biases, the 2D ZrB2 shows a similar electrical
transport along zigzag and armchair directions as electric current propagates
mostly via the metallic Zr-Zr bonds. However, it shows an electrical anistropy
under high biases, and its I-V curves along zigzag and armchair directions
diverge as the bias voltage is higher than 1.4 V, as more directional B-B
transmission channels are opened. Importantly, both z-ZrB2 and a-ZrB2 show a
pronounced negative differential conductance (NDC) effect and hence they can be
promising for the use in NDC-based nanodevices.
