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

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.