title: Multiple Dirac Points and Hydrogenation-Induced Magnetism of Germanene Layer on Al (111) Surface.
abstract: A continuous germanene layer grown on the Al (111) surface has recently been achieved in experiment. In this work, we investigate its structural, electronic, and hydrogenation-induced properties through first-principles calculations. We find that despite having a different lattice structure from its free-standing form, germanene on Al (111) still possesses Dirac points at high-symmetry K and K' points. More importantly, there exist another three pairs of Dirac points on the K(K')-M high-symmetry lines, which have highly anisotropic dispersions due to the reduced symmetry. These massless Dirac Fermions become massive when spin-orbit coupling is included. Hydrogenation of the germanene layer strongly affects its structural and electronic properties. Particularly, when not fully hydrogenated, ferromagnetism can be induced due to unpaired local orbitals from the unsaturated Ge atoms. Remarkably, we discover that the one-side semihydrogenated germanene turns out to be a two-dimensional half-semimetal, representing a novel state of matter that is simultaneously a half-metal and a semimetal.
authors.affiliation: Strong-field and Ultrafast Photonics Lab, Institute of Laser Engineering, Beijing University of Technology , Beijing 100124, China.|College of Physics and Communication Electronics, Jiangxi Normal University , Nanchang 330022, China.
authors.forename: G
authors.initials: G
authors.lastname: Liu
authors.affiliation: Strong-field and Ultrafast Photonics Lab, Institute of Laser Engineering, Beijing University of Technology , Beijing 100124, China.
authors.forename: S B
authors.initials: SB
authors.lastname: Liu
authors.affiliation: College of Physics and Communication Electronics, Jiangxi Normal University , Nanchang 330022, China.
authors.forename: B
authors.initials: B
authors.lastname: Xu
authors.affiliation: College of Physics and Communication Electronics, Jiangxi Normal University , Nanchang 330022, China.
authors.forename: C Y
authors.initials: CY
authors.lastname: Ouyang
authors.affiliation: Strong-field and Ultrafast Photonics Lab, Institute of Laser Engineering, Beijing University of Technology , Beijing 100124, China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Song
authors.affiliation: Research Laboratory for Quantum Materials and EPD Pillar, Singapore University of Technology and Design , Singapore 487372, Singapore.|School of Physics, Beijing Institute of Technology , Beijing 100081, China.
authors.forename: S
authors.initials: S
authors.lastname: Guan
authors.affiliation: Research Laboratory for Quantum Materials and EPD Pillar, Singapore University of Technology and Design , Singapore 487372, Singapore.
authors.forename: Shengyuan A
authors.initials: SA
authors.lastname: Yang
keywords: Dirac point; germanene; graphene; semi-metal