▎ 摘　　要

The electronic and magnetic properties of the zigzag edge graphene nanoribbon with a topological line defect (LD-ZGNR) have been studied under an external strain along ribbon axis by using first-principle calculations. It is found that the applied strain induces the local magnetic moments on the line defect, whose coupling with those on the edges leads to a turnover of the spin polarization on one edge, making the LD-ZGNR become a ferromagnetic (FM) metal at a large enough strain. When the strain increases to larger than 16%, a transition from a FM metal to a FM semiconductor will happen. Our calculation results suggest a possible way to tune the magnetic and transport properties of the LD-ZGNR by applying the strain, which is very useful for applications of the graphene ribbon in spintronics and electromechanical devices.