The ternary compound bismuth telluroiodide (BiTeI) is new class of polar or Janus vdW crystals. They exhibit rather unique structural characteristics in that each layer consists of Bi atoms sandwiched in between tellurium (Te) and iodine (I) atoms as shown in the figures. Because of layer difference in the surface potential within each vdW layer, there is a large electric field confined in the layers. This field has been shown to lead to giant Rashba effects, spin orbit coupling (due to large atomic mass), as well as spintronic properties. This layered crystal structure has the trigonal space group of P3m1 and lacks the space inversion symmetry. Our crystals are synthesized using our patent pending graded Bridgman growth technique which is designed for high purity (99.9999%) vdW crystal growth. Due to complexities in the growth process, these unique materials are extremely difficult to synthesize and each order comes with mm sized crystals with guaranteed Janus layer formation, easy exfoliation characteristics, environmental stability, and minimal defects.
The properties of BiTeI Janus/Polar crystals：