报告题目：Dirac semimetal properties of K doped black phosphorus

报 告 人：Hyoung Joon Choi, Department of Physics, Yonsei University, Korea

报告时间：2016年1月21日16：00

报告地点：理科楼C302

报告摘要：Thin flakes of black phosphorus (BP) are a two-dimensional (2D) semiconductor whose energy gap is predicted being sensitive to the number of layers and external perturbations. Very recently, it was found that a simple method of potassium (K) doping on the surface of BP closes its band gap completely, producing a Dirac semimetal state with a linear band dispersion in the armchair direction and a quadratic one in the zigzag direction [1]. Here, based on first-principles density functional calculations, we predict that beyond the critical K density of the gap closure, 2D massless Dirac fermions (i.e. Dirac cones) emerge in Kdoped few-layer BP, with linear band dispersions in all momentum directions, and the electronic states around Dirac points have chiral pseudospins and Berry's phase [2]. These features are robust with respect to the spin-orbit interaction and may lead to graphene-like electronic transport properties with greater flexibility for potential device applications.

[1] J. Kim, S. S. Baik, S. H. Ryu, Y. Sohn, S. Park, B.-G. Park, J. Denlinger, Y. Yi, H. J. Choi, and K. S. Kim, Science 349, 723 (2015)

[2] S. S. Baik, K. S. Kim, Y. Yi, and H. J. Choi, Nano Letters 15, 7788 (2015)