Applied Physics Letters
We present a systematic first-principles calculation on the atomistic structural variation for armchair-edge graphene nanoribbons (AGNRs) under a small planar uniaxial strain along armchair and zigzag directions, respectively. Interestingly, it is found that asymmetric AGNRs are more sensitive to the external strain with more types of carbon-carbon bonds and angles, while symmetric ones show less types of bonds and angles under the same strain. This difference is attributed to the symmetric property of AGNRs combining with the bond theory. Our findings may be useful in further understanding of GNRs under strain and in designing nanoelectromechanical devices based on GNRs. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702842]
关键词:
electronic-structure
Journal of Applied Physics
Using the first-principles density functional method, we predict the half-metallic ferromagnetism of ZnCrAs(2) in chalcopyrite structure with a magnetic moment of 2.0 mu(B) per formula unit. The band structures show the spin-up electrons are metallic, but the spin-down bands have a gap of 1.01 eV, and the energy gap between the top of valence band and the Fermi level is 0.52 eV. Based on the Heisenberg model, the magnetic exchange constants between Cr-Cr interactions for the first three nearest-neighbors were obtained, all three have the ferromagnetic character. From the estimate of mean-field approximation, the chalcopyrite ZnCrAs(2) is a possible room-temperature ferromagnet. (C) 2011 American Institute of Physics. [doi:10.1063/1.3530728]
关键词:
electronic-structure
