Observation and Control of the Magnetic Photogalvanic Effect from Strongly Bound Excitons

Photogalvanic effects arising from the quantum geometry of noncentrosymmetric materials are promising for next-generation light-harvesting devices that do not require a built-in electric field. Recent theories predict photogalvanic currents generated in magnetic systems with spin-dependent symmetry breaking as well as by bound exciton states, allowing for potential magnetic field control of the photoresponse and enhanced detection of deep sub-gap signals, respectively. We demonstrate the magnetic photogalvanic effect in a bilayer CrI3 tunnel junction with both magnetic field switching and electric field tuning of interlayer symmetry. By controlling for the polarization and energy of light illumination, we disentangle the shift and injection current contributions and find that the peak response occurs under resonant excitation of strongly bound excitons in CrI3. Our results can be captured within a many-body framework of the photogalvanic effect, while our devices function as tunable, multispectral helicity- and polarization-sensitive detectors that highlight the potential of 2D magnets for future optoelectronic applications.