Imaging ultrafast multiferroic dynamics in BiFeO3

The sub-picosecond control of ferroic orders represents a key frontier in the development of next-generation ultrafast technologies. Among the various prototypical systems, magnetoelectric multiferroic materials, exhibiting coupled ferroelectric and antiferromagnetic orders, stand out due to their terahertz magnetic dynamics, which can be actuated by ultrafast electrical transients. In this work, we present the implementation of time-resolved second-harmonic generation imaging, designed to probe the coupled ferroelectric and antiferromagnetic dynamics on sub-picosecond timescales, with sub-micrometer spatial resolution. This nonlinear optical technique has emerged as a powerful and versatile tool for addressing key challenges in the physics of ferroic oxides. Here, we decipher the ultrafast multiferroic dynamics of an epitaxial BiFeO3 thin film excited by near-infrared femtosecond laser pulses. We are able to depict its ultrafast antiferromagnetic demagnetization within distinct antiferromagnetic domains. Our results open the path toward the ultrafast manipulation of antiferromagnetic states in magneto-electric systems.