Thermal conductivity suppression by extreme stress gradients in bent cracked silicon nanowires

Precise control of thermal transport is crucial for increasing the energy efficiency and reliability of modern electronic devices. While the effects of moderate strain gradients on thermal conductivity have been studied previously, the underlying mechanisms governing heat transport under extreme stress gradients (greater than 1 GPa/Å) remain elusive. In this study, we use molecular dynamics simulations and introduce a bending-induced loading method on cracked silicon nanowires to generate localized extreme stress gradients near the crack tip. When subjected to a 12% bending strain (with the stress at the crack tip exceeding 1 GPa/Å), the cracked nanowire exhibited a 20.1% reduction in thermal conductivity. This is more than double the 8.3% reduction observed in its crack-free counterpart. Detailed atomistic analysis reveals that extreme stress gradients break lattice translational symmetry, disrupt vibrational coherence, and intensify phonon scattering. These effects eventually promote phonon localization and create a thermal transport bottleneck that significantly suppresses heat conduction. This study not only explores the microscopic physical mechanisms underlying the influence of extreme stress gradients on thermal conductivity, filling existing theoretical gaps, but also provides new insights for heat dissipation design and material development for microelectronics in extreme environments.