Electronic effects of localized strain in graphene

Strain is a key tuning parameter in solid-state systems, but most studies focus on strain fields extending over tens of nanometers or more. Here we investigate the extreme limit of ultra-localized strain in graphene, introduced through bond defects generated by ultralow-energy implantation of noble gas ions. Using molecular dynamics simulations, Raman spectroscopy, and scanning tunneling microscopy, we identify the formation and thermal stability of bond defects that locally stretch only a few C-C bonds without removing or substituting atoms. Tight-binding calculations reveal that such bond defects induce local charge trapping, leading to substantial Fermi-level shifts. Synchrotron-based angle-resolved photoemission spectroscopy directly confirms these predictions: even at modest defect densities (∼1012cm−2), the graphene Fermi level shifts by up to 0.3 eV. This strong effect is remarkable given that it is achieved without altering graphene’s composition, in contrast to conventional impurity doping or vacancy formation. Upon thermal annealing, the electronic structure recovers towards the pristine state, showing that these effects can be tuned and reversed. Our results establish bond defects as a new class of functional disorder in graphene, capable of strongly modifying its electronic properties solely by bond rearrangement.