Search

In an unconstrained elastic body, emergence of zero natural frequencies is an expectable outcome on account of the body's ability to purely translate or rotate with no structural deformation. Recent advances in literature have pushed such conventional definition and demonstrated properties transcending typical zero-frequency modes, such as localization of deformation at a structural edge or corner. In this paper, a spring–mass honeycomb lattice with an elastic foundation, referred to here as mechanical graphene, is designed to exhibit zero-frequency corner modes. A central element in the proposed design is the elastic foundation, and the zero-frequency corner modes are enabled by intricate modulation of the elastic-foundation's stiffness. These modes are proven to have their origins from the dynamics of a diatomic chain, made from a single strip of the mechanical graphene with free boundaries. Different shapes of finite mechanical graphene with free boundaries are considered and conditions leading to the manifestation of corner modes are correlated with the angle of corners and stiffness of springs supporting them. Finally, the effect of defects on zero-frequency corner modes is briefly discussed, demonstrating robustness against structural defects that are distant from corners. • The concept of zero-frequency corner modes in a mechanical graphene is introduced. • Elastic foundation of positive-negative springs enables zero-frequency corner modes. • Corner modes origin is connected to edge modes in a comparable diatomic lattice. • Corner modes only occur in mechanical graphene having 60°-angle corners. • Theory is verified numerically using different shapes of mechanical graphene. [Display omitted] [ABSTRACT FROM AUTHOR]

Next, the researchers applied different magnetic fields to the graphene to measure how its magnetoresistance changed. This is partly down to graphene's electrons and holes being highly mobile and therefore sensitive to tiny changes in an external magnetic field, the researchers write in their paper. Its unparalleled ability to increase or decrease its electrical resistance in response to a magnetic field could one day have applications for how we store data. [Extracted from the article]