2025/07/23 by Jung, Gwan Yeong, Ren, Guodong, Omprakash, Pravan +2
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Optics (physics.optics)
paper · doi:10.48550/arxiv.2507.17632
Birefringence (Δn) is the dependence of the refractive index of a material on the polarization of light travelling through it. Birefringent materials are used as polarizers, waveplates, and for novel light-matter coupling. While several birefringent materials exist, only a handful of them show large Δn > 0.3, and are primarily limited to the infrared region. The variation of Δn across diverse materials classes and strategies to achieve highly birefringent materials with transparency covering different regions of the electromagnetic spectrum are missing. We have calculated the Δn of 967 non-cubic, formable crystals having vastly different structures, polyhedral connectivity and chemical compositions. From this set of compounds, we have screened highly birefringent crystals (Δn greater than 0.3) having transparency in different regions of the electromagnetic spectrum. The screened compounds belong to several families such as A3'MN3, AMO2, AN3, and A'N6 (A = Li, Na, K; A'= Ca, Sr, Ba; M = V, Nb, Ta). By analyzing the electronic structures of these compounds, we have distilled rules to enable the design of crystals with large Δn.