English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Quantum thermal transport in armchair and zig-zag graphene nanoribbons areinvestigated in the presence of single atomic vacancies and subject todifferent boundary conditions. We start with a full comparison of the phononpolarizations and energy dispersions as given by a fifth-nearest-neighborforce-constant model (5NNFCM) and by elasticity theory of continuum membranes(ETCM). For free-edges ribbons we discuss the behavior of an additionalacoustic edge-localized flexural mode, known as fourth acoustic branch (4ZA),which has a small gap when it is obtained by the 5NNFCM. Then, we show thatribbons with supported-edges have a sample-size dependent energy gap in thephonon spectrum which is particularly large for in-plane modes. Irrespective tothe calculation method and the boundary condition, the dependence of the energygap for the low-energy optical phonon modes against the ribbon width W is foundto be proportional to 1/W for in-plane, and 1/W$^2$ for out-of-plane phononmodes. Using the 5NNFCM, the ballistic thermal conductance and itscontributions from every single phonon mode are then obtained by the nonequilibrium Green's function technique. We found that, while edge and centrallocalized single atomic vacancies do not affect the low-energy transmissionfunction of in-plane phonon modes, they reduce considerably the contributionsof the flexural modes. On the other hand, in-plane modes contributions arestrongly dependent on the boundary conditions and at low temperatures can behighly reduced in supported-edges samples. These findings could open a route toengineer graphene based devices where it is possible to discriminate therelative contribution of polarized phonons and to tune the thermal transport onthe nanoscale.

The role of atomic vacancies and boundary conditions on ballistic thermal transport in graphene nanoribbons