71 research outputs found
Anisotropy of the Stone-Wales Defect and Warping of Graphene Nano-ribbons: A First-principles Analysis
Stone-Wales (SW) defects, analogous to dislocations in crystals, play an
important role in mechanical behavior of -bonded carbon based materials.
Here, we show using first-principles calculations that a marked anisotropy in
the interaction among the SW defects has interesting consequences when such
defects are present near the edges of a graphene nano-ribbon: depending on
their orientation with respect to edge, they result in compressive or tensile
stress, and the former is responsible to depression or warping of the graphene
nano-ribbon. Such warping results in delocalization of electrons in the defect
states.Comment: 8 page
Prediction of Magnetoelectric Multiferroic Janus Monolayers VOXY(X/Y = F, Cl, Br, or I, and XY) with in-plane ferroelectricity and out-of-plane piezoelectricity
Multifunctional two-dimensional (2D) multiferroics are promising materials
for designing low-dimensional multipurpose devices. The key to
multifunctionality in these materials is breaking the space-inversion and the
time-reversal symmetry, which results in spontaneous electric polarization and
magnetization in the same phase. A new class of 2D materials, Janus 2D
materials, has emerged, which works on a similar principle of breaking
out-of-plane symmetry to invoke new exciting functionalities in the 2D
materials, such as an out-of-plane piezoelectric polarization. In this work, a
new group of 2D multiferroic Janus monolayers VOXY (X/Y = F, Cl, Br, or I, and
XY) is derived by breaking the out-of-plane symmetry in the parent
multiferroics VOX (X = F, Cl, Br, or I). The structural, magnetic, and
ferroelectric properties of multiferroics VOX are compared with their Janus
derivatives. We calculated in-plane and out-of-plane piezoelectric polarization
for VOX and VOXY series, where VOFCl, VOFBr, VOFI, and VOClI are found to
have significant out-of-plane piezoelectric polarization. Our theoretical work
predicts a new series of 2D multiferroic materials and encourages their further
investigation for high-performance nanoelectronic devices.Comment: 13 pages, 5 figures, 5 tables, and Supplemental Materia
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