The role of substrate on stabilizing new phases of two-dimensional tin

In this work, we investigate the role of substrates in determining the morphologies and electronic structures of two-dimensional (2D) Sn. We use Ir(111) and 2D hexagonal boron nitride (h-BN) predeposited on Ir(111) as substrates. The latter contains Moiré patterns with varying binding strength between h-BN and metal. Using scanning tunneling microscopy and first-principles calculations, we reveal the distinct morphologies of 2D Sn on different substrates. Of particular interest, we discover a new √7 × √7 Sn phase, originating from the local charge transfer with metal beneath the 'decoupling' h-BN monolayer at the strongly interacting Moiré region. To the best of our knowledge, this work demonstrates, for the first time via combined experimental and theoretical approach, that new 2D Sn phases can be achieved using Moiré patterns on h-BN/metal. This finding should be instrumental in the development of 2D-based topological materials.