Symposium CH02: Emerging Optoelectronic and Quantum Materials—Advanced Multimodal Characterizations

Xiaoyang Zhu, Columbia University

Ferromagnetic 2D vdW Semiconductors

Written by Md Afzalur Rab

Xiaoyang Zhu presented his group's research on two-dimensional van der Waals materials with multifunctional properties, focusing on semiconductors that exhibit magnetic and ferroelectric behaviors. The team explored how various physical phenomena, such as magnetism and electric polarization, interact in a coupled manner to enable new mechanisms for control and sensing at the nanoscale. Their work contributes to the broader field of quantum materials and offers insights into novel ways to manipulate these properties for advanced applications. This research is particularly relevant for emerging technologies in areas such as sensing, data storage, and wireless communication.

In their investigation of the magnetic semiconductor CrSBr, the team discovered a strong interaction between excitons—electron–hole pairs—and magnetic order, leading to magneto-exciton coupling. This coupling allowed for the detection of magnons, or spin waves, at extremely low energy ranges using optical techniques. Similarly, in the ferroelectric material NbOI₂, the researchers observed a large optical rectification effect, which enables the material to convert light into terahertz radiation more efficiently than conventional materials. They also identified an unusual coupling between transverse optical phonons and excitons, contrasting with typical longitudinal optical phonon behavior. These findings, enabled by advanced ultrafast optical methods, reveal new possibilities for manipulating low-energy quantum excitations, advancing the design of multifunctional materials with complex, tunable responses to external stimuli.