Manipulating Photogalvanic Effects in Two-Dimensional\nMultiferroic Breathing Kagome Materials

Multiferroic\nmaterials, known for their multiple tunable orders,\npresent an exceptional opportunity to manipulate nonlinear optical\nresponses that are sensitive to symmetry. In this study, we propose\nleveraging electric and magnetic fields to selectively control and\nswitch specific types of photogalvanic effects in two-dimensional\nmultiferroic breathing kagome materials. Taking monolayer Nb<sub>3</sub>I<sub>8</sub> as an example, we demonstrate that the shift current,\ncharacterized by the real-space shift of electrons and holes, is predominantly\nunaffected by magnetic order. In contrast, injection current, featured\nby quantum metric dipole in momentum space, is closely related to\nvalley polarization, which can be controlled by a magnetic field.\nFurthermore, both photocurrents can be reversed by an out-of-plane\nelectric field via lattice breathing. Our findings reveal the potential\nof multiferroic breathing kagome structures for multifunctional optoelectronic\napplications and sensors.