Exfoliation of single layer BiTeI flakes

TL;DR

This paper reports the successful exfoliation of single-layer BiTeI, a 2D material with strong spin-orbit interaction, stable at room temperature, promising for spintronic applications.

Contribution

First demonstration of exfoliating single-layer BiTeI, combining experimental and theoretical analysis of its stability and properties.

Findings

Achieved stable single-layer BiTeI flakes of 100 μm size.

Confirmed giant Rashba splitting and spin-momentum locking in 2D BiTeI.

Demonstrated ambient stability of exfoliated flakes.

Abstract

Spin orbit interaction can be strongly boosted when a heavy element is embedded into an inversion asymmetric crystal field. A simple structure to realize this concept in a 2D crystal contains three atomic layers, a middle one built up from heavy elements generating strong atomic spin-orbit interaction and two neighboring atomic layers with different electron negativity. BiTeI is a promising candidate for such a 2D crystal, since it contains heavy Bi layer between Te and I layers. Recently the bulk form of BiTeI attracted considerable attention due to its giant Rashba interaction, however, 2D form of this crystal was not yet created. In this work we report the first exfoliation of single layer BiTeI using a recently developed exfoliation technique on stripped gold. Our combined scanning probe studies and first principles calculations show that SL BiTeI flakes with sizes of 100 $\mu$m were achieved which are stable at ambient conditions. The giant Rashba splitting and spin-momentum locking of this new member of 2D crystals open the way towards novel spintronic applications and synthetic topological heterostructures.