Abstract The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.
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Emergent optical nonreciprocity and chirality-controlled magneto-optical resonance in a hybrid magneto–chiral metamaterial
Broken spatial and time reversal symmetries in materials often give rise to new emergent phenomena in the interaction between light and matter. The combination of chirality and broken time reversal symmetry in a magnetic field leads to magneto–chiral phenomena, such as the nonreciprocity of transmission. Here, we construct a terahertz hybrid metamaterial that combines the natural optical activity of a chiral metallic gammadion bilayer and the magneto-optical activity of semiconductor indium antimonide in a magnetic field. We report a resonant magneto–chiral effect that leads to polarization-independent nonreciprocal optical transmittance. Furthermore, we discover a magneto-optical Faraday effect that is resonantly controlled by the natural optical activity of the chiral gammadion bilayer. Unlike optical activity due to chirality, the novel Faraday effect is odd under time reversal. Both phenomena are activated by a modest magnetic field, which may open doors for their potential applications in polarization-independent optical isolation and highly efficient polarization control at terahertz frequencies.
more » « less- Award ID(s):
- 1919944
- NSF-PAR ID:
- 10392794
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optica
- Volume:
- 10
- Issue:
- 2
- ISSN:
- 2334-2536
- Page Range / eLocation ID:
- Article No. 155
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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