Extensive investigations on the Moir\'e magic-angle have been conducted in twisted bilayer graphene, unlocking the mystery of unconventional superconductivity and insulating states. In analog to magic angle, here we demonstrate the new concept of magic-strain in graphene systems by judiciously tailoring mechanical relaxation (stretch and compression) which is easier to implement in practice. We elucidate the interplay of strain-induced effects and delve into the resulting unconventional superconductivity or semimetal-insulator transition in relaxation-strained graphene, going beyond the traditional twisting approach. Our findings reveal how relaxation strain can trigger superconducting transitions (with an ultra-flat band at the Fermi level) or the semimetal-insulator transition (with a gap opening at the K point of 0.39eV) in both monolayer and bilayer graphene. These discoveries open up a new branch for correlated phenomena and provide deeper insights into the underlying physics of superconductors, which positions graphene as a highly tunable platform for novel electronic applications.
@article{arxiv.2407.16044,
title = {Unconventional superconductivity in magic-strain graphene superlattices},
author = {Qingxiang Ji and Bohan Li and Johan Christensen and Changguo Wang and Muamer Kadic},
journal= {arXiv preprint arXiv:2407.16044},
year = {2024}
}