  The ideal strength is the maximum stress a material can withstand, and it is
an important intrinsic property for structural applications. Griffith strength
limit ~E/9 is the best known upper bound of this property for a material loaded
in tension. Here we report that stanene, a recently fabricated two-dimensional
material, could approach and possibly exceed this limit from a theoretical
perspective. Utilizing first-principles density functional theory, we
investigated the nonlinear elastic behavior of stanene and found that its
strength could reach ~E/7.4 under uniaxial tension in both armchair and zigzag
directions without incurring phonon instability or mechanical failure. The
unique mechanical properties of stanene are further appreciated by comparisons
with two other Group-IV 2D materials, graphene and silicene.
