2D tetragonal ZnB: nodal-line semimetal with good transport properties

Abstract

Abstract Nodal-line semimetals have brought a hot-spot of research due to its novel properties and great potential application in spin electronics. It is more challenging to find 2D nodal-line semimetals that can resist the spin-orbit coupling (SOC) effect. Here, we predict that 2D tetragonal ZnB is the nodal-line semimetal with great transport properties. There are two crossing bands centered on S point at Fermi surface without SOC, which are mainly composed of p xy orbitals of Zn and B atoms and the p z orbitals of B atom. Therefore, the system presents nodal line centered on S point in its Brillouin zone (BZ). And the nodal line is protected by the horizontal mirror symmetry Mz. We further examined robustness of nodal line under biaxial strain by applying up to -4% in-plane compressive strain and 5% tensile strain on ZnB monolayer, respectively. The transmission along a direction is significantly stronger than that along b direction in the conductive channel. The current in a direction is as high as 26.63 μA at 0.8 V and that in b direction reaches 8.68 μA at 0.8 V. It is interesting that transport characteristics of ZnB are negative differential resistance (NDR) effect after 0.8 V along a (b) direction. The results provide ideal platform for research of fundamental physics of 2D nodal-line fermions and nanoscale spintronics as well as design of new quantum devices.