A groundbreaking study conducted by Professor Sheng Zhigao and his research team at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has shed light on the intriguing nonlinear magnetic second harmonic generation (MSHG) induced by the ferromagnetic order in monolayer CrPS4. This discovery, detailed in a recent publication in Advanced Optical Materials, marks the first observation of its kind and has significant implications for the field of optoelectronics.
Second harmonic generation (SHG) is a nonlinear optical phenomenon that is highly sensitive to symmetry breaking in materials. Traditionally, SHG has been observed in crystals with broken symmetry (i type), with only weak occurrences in magnetic systems (c type), limiting its usefulness in optical devices. However, the emergence of magnetic two-dimensional van der Waals materials has sparked interest due to their unique properties, yet their nonlinear optical properties, especially the relationship between SHG and magnetic order, remain largely unexplored.
The research team’s investigation into the magnetic order-related SHG effects in the two-dimensional antiferromagnetic material CrPS4 yielded fascinating results. Unlike in bulk and even-layered CrPS4, where the antiferromagnetic order did not generate any c type SHG effects, the researchers discovered a substantial c type SHG effect induced by monolayer ferromagnetic order in odd-layered CrPS4. This groundbreaking observation of ferromagnetic order-induced c type SHG effects in a 2D magnet under the electric-dipole approximation is attributed to the dual breaking of spatial and time inversion symmetries.
Of particular significance is the team’s discovery that the ferromagnetic order induced c type SHG in monolayer CrPS4 rivals the signal strength of i type SHG resulting from crystal structural symmetry breaking. This finding is unprecedented among known magnetic materials and holds promise for the development of advanced optoelectronic devices with enhanced nonlinear magneto-optical properties.
Professor Sheng Zhigao and his team’s pioneering research on the nonlinear magneto-optical properties of monolayer CrPS4 has opened up new avenues for exploring the intricate interplay between magnetic order and optical behavior in two-dimensional materials. This groundbreaking study not only expands our understanding of nonlinear optical effects but also paves the way for innovative advancements in optoelectronics.