Observation of magnetically coupled electro-optic effect in LiNbO3/LiTaO3 at room temperature

Abstract

The magnetoelectric coupling effect serves as a crucial bridge between electrical and magnetic order parameters in condensed matter physics, forming the physical basis for the development of next-generation low-power information storage and sensing technologies. However, material systems exhibiting this effect at room temperature are extremely rare, and the coupling strength is typically very weak, which has long hindered the practical application of such phenomena despite their rich tunability. Here, we break this by reporting a pronounced magnetoelectric phenomenon,the magnetically coupled EO effect in the classic ferroelectric optical materials LiNbO3 and LiTaO3. We trace its origin to an unexpected source,the problematic direct current drift,a major reliability issue in photonic integrated circuits. We unambiguously demonstrate that this drift stems not from mobile ions but from defect-bound unpaired electrons, whose slow polarization relaxation is quenched upon the magnetic-field-induced formation of a room-temperature skyrmion states, as directly visualized by Lorentz transmission electron microscopy. This collective spin ordering not only solves the decades-old drift problem but also transforms the defect states into a magnetically responsive platform, exhibiting an efficiency up to 34 pm/V in LiNbO3 and 15 pm/V in LiTaO3-an orders-of-magnitude enhancement over conventional room-temperature magnetoelectric responses and even surpassing the materials' intrinsic Pockels coefficients. We also measured the magnetic response of this additional electro-optical effect and found that under the condition of applying a magnetic field of 0.1 T, an electro-optical coefficient adjustment of about 8 pm/V can be achieved (0.008 pm/V/Oe), which is equivalent to 30% of the electro-optical coefficient of LiNbO3 itself.