A novel quasi-one-dimensional topological insulator theoretically predicted and experimentally confirmed by the team of Oleg V. Yazyev

MARVEL researchers in the group of Professor Oleg V. Yazyev at the Institute of Theoretical Physics of EPFL have theoretically predicted and experimentally confirmed, the  topological insulator behaviour of the beta-phase of  the  quasi-one-dimensional bismuth iodide, Bi4I4.

Topological surface states in bismuth iodide as seen by angle-resolved photoemission spectroscopy

A joint theoretical-experimental work led to the discovery of a novel topological insulator phase in the binary bismuth iodide, beta-Bi4I4.    

The electronic structure calculations (DFT and GW) and the angle-resolved photoemission spectroscopy measurements revealed a highly anisotropic band-crossing feature. The resistivity measurements confirmed the small band gap in this compound.  The work has been published on Nature Materials (2015).