Phonon excitation and instabilities in biased graphene nanoconstrictions

TY - JOUR

T1 - Phonon excitation and instabilities in biased graphene nanoconstrictions

AU - Gunst, Tue

AU - Lu, Jing Tao

AU - Hedegård, Per

AU - Brandbyge, Mads

PY - 2013/10/11

Y1 - 2013/10/11

N2 - We investigate how a high current density perturbs the phonons in a biased graphene nanoconstriction coupled to semi-infinite electrodes. The coupling to electrode phonons, electrode electrons under bias, Joule heating, and current-induced forces is evaluated using first principles density functional theory and nonequilibrium Green's function calculations. We observe a strongly nonlinear heating of the phonons with bias and breakdown of the harmonic approximation when the Fermi level is tuned close to a resonance in the electronic structure of the constriction. This behavior is traced back to the presence of negatively damped phonons driven by the current. The effects may limit the stability and capacity of graphene nanoconstrictions to carry high currents.

AB - We investigate how a high current density perturbs the phonons in a biased graphene nanoconstriction coupled to semi-infinite electrodes. The coupling to electrode phonons, electrode electrons under bias, Joule heating, and current-induced forces is evaluated using first principles density functional theory and nonequilibrium Green's function calculations. We observe a strongly nonlinear heating of the phonons with bias and breakdown of the harmonic approximation when the Fermi level is tuned close to a resonance in the electronic structure of the constriction. This behavior is traced back to the presence of negatively damped phonons driven by the current. The effects may limit the stability and capacity of graphene nanoconstrictions to carry high currents.

U2 - 10.1103/PhysRevB.88.161401

DO - 10.1103/PhysRevB.88.161401

M3 - Journal article

SN - 2469-9950

VL - 88

JO - Physical Review B

JF - Physical Review B

IS - 16

M1 - 161401

ER -