A recent study led by Professor Sheng Zhigao at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has shed light on the strong nonlinear magnetic second harmonic generation (MSHG) induced by the ferromagnetic order in monolayer CrPS4. This groundbreaking research, published in Advanced Optical Materials, explores the intricate relationship between magnetic order and second harmonic generation in two-dimensional materials.
Second harmonic generation (SHG) is a fascinating nonlinear optical effect that is sensitive to symmetry breaking in materials. While this phenomenon was first observed in crystals with broken symmetry (i-type), it is also found in magnetic systems (c-type), albeit in a weaker form. This limitation has hindered the potential use of SHG in optical devices. The study by Sheng’s team delves into the unexplored nonlinear optical properties of two-dimensional van der Waals materials, particularly focusing on the connection between SHG and magnetic order.
The research team made some significant discoveries during their investigation. In bulk and even-layered CrPS4, the antiferromagnetic order did not result in any c-type SHG effects. However, an intriguing observation was made in odd-layered CrPS4, where a substantial c-type SHG effect induced by monolayer ferromagnetic order was observed. This notable finding marks the first instance of ferromagnetic order-induced c-type SHG effects in a 2D magnet under the electric-dipole approximation.
The implications of this research extend beyond theoretical insights. The team found that the ferromagnetic order-induced c-type SHG exhibited a signal strength comparable to that of i-type SHG, which typically arises from the breaking of crystal structural symmetry. This rarity among magnetic materials opens up new possibilities for utilizing two-dimensional materials in optoelectronic devices.
The study led by Professor Sheng Zhigao provides a deeper understanding of the intricate link between magnetic order and second harmonic generation in two-dimensional materials. By uncovering the unprecedented ferromagnetic order-induced c-type SHG effects, this research not only advances our knowledge of nonlinear optical properties but also paves the way for novel applications in optoelectronics.
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