Light induced symmetry change in Cr₂O₃ by time resolved second harmonic generation

The development of ultrafast lasers has offered an alternative way to alter the properties of materials in addition to conventional stimulus. In this work, we study anti-ferromagnetic Cr2O3, which is known as a typical magnetoelectric, with time resolved second harmonic generation (SHG). We are able to change the symmetry of Cr₂O₃ transiently with a near infrared pump below the electronic gap. The symmetry changes are monitored by rotational anisotropy SHG. Our work demonstrates an effective way to manipulate the properties of materials on ultrafast time scales.