Magnetism of bilayer graphene with vacancies

At the nanoscale defects (vacancies) can be useful for generating novel materials and devices. In this paper we discuss how a bi-vacancy orientation in bilayer graphene influences the total magnetization of the system.  The spin-polarized density functional theory as implemented in the Quantum Espresso code is used to calculate the total magnetization for the case of graphene sheets with  the same or different vacancy distributions. Important results are obtained:  reduction of the magnetic moment due to the interlayer bonding in AA bilayer stack with a double vacancy in each graphene layer  on the top of each other; out-off plane arrangement of the carbon atoms in the vicinity of the vacanices; opening of a gap in the band structure due to vacancies. It could be expected that the temperature and the interface will further influence the life-time of the magnetic state but the possibility of switching between non-magnetic, antiferromagnetic and ferromagnetic states as a result of mutual rotation of the defective layers remains. Copyright © 2017 VBRI Press