High pressure chemistry is known to inspire the creation of unexpected new classes of compounds with exceptional properties. Here we report the synthesis at ~90 GPa of novel beryllium polynitrides, monoclinic and triclinic BeN4. The triclinic phase, upon decompression to ambient conditions, transforms into a compound with atomic-thick BeN4 layers interconnected via weak van der Waals bonds consisting of polyacetylene-like nitrogen chains with conjugated {\pi}-systems and Be atoms in square-planar coordination. Theoretical calculations for a single BeN4 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 BeN4 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.
@article{arxiv.2010.15774,
title = {High-pressure synthesis of Dirac materials: layered van der Waals bonded BeN$_4$ polymorph},
author = {Maxim Bykov and Timofey Fedotenko and Stella Chariton and Dominique Laniel and Konstantin Glazyrin and Michael Hanfland and Jesse S. Smith and Vitali B. Prakapenka and Mohammad F. Mahmood and Alexander F. Goncharov and Alena V. Ponomareva and Ferenc Tasnádi and Alexei I. Abrikosov and Talha Bin Masood and Ingrid Hotz and Alexander N. Rudenko and Mikhail I. Katsnelson and Natalia Dubrovinskaia and Leonid Dubrovinsky and Igor A. Abrikosov},
journal= {arXiv preprint arXiv:2010.15774},
year = {2021}
}