Negative differential conductance effect and electrical anisotropy of 2D ZrB2 monolayers

Abstract

Two-dimensional (2D) metal-diboride ZrB2 monolayers was predicted theoretically as a stable new electronic material (Lopez-Bezanilla 2018 Phys. Rev. Mater. 2 011002). 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.