High-Pressure Synthesis of Dirac Materials: Layered van der Waals Bonded <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mi>BeN</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:math> Polymorph
Maxim Bykov, Timofey Fedotenko, Stella Chariton, Dominique Laniel, Konstantin Glazyrin, Michael Hanfland, Jesse S. Smith, Vitali B. Prakapenka, Mohammad F. Mahmood, Alexander F. Goncharov, Alena V. Ponomareva, Ferenc Tasnádi, Alexei I. Abrikosov, Talha Bin Masood, Ingrid Hotz, А. Н. Руденко, Mikhail I. Katsnelson, Natalia Dubrovinskaia, Leonid Dubrovinsky, Igor A. Abrikosov
Abstract
High-pressure chemistry is known to inspire the creation of unexpected new classes of compounds with exceptional properties. Here, we employ the laser-heated diamond anvil cell technique for synthesis of a Dirac material BeN_{4}. A triclinic phase of beryllium tetranitride tr-BeN_{4} was synthesized from elements at ∼85 GPa. Upon decompression to ambient conditions, it transforms into a compound with atomic-thick BeN_{4} layers interconnected via weak van der Waals bonds and consisting of polyacetylene-like nitrogen chains with conjugated π systems and Be atoms in square-planar coordination. Theoretical calculations for a single BeN_{4} layer show that its electronic lattice is described by a slightly distorted honeycomb structure reminiscent of the graphene lattice and the presence of Dirac points in the electronic band structure at the Fermi level. The BeN_{4} layer, i.e., beryllonitrene, represents a qualitatively new class of 2D materials that can be built of a metal atom and polymeric nitrogen chains and host anisotropic Dirac fermions.