Ba and BaOx surface structures on Au(111)

► Surface structures of ultrathin Ba and BaOx films on Au(111) substrate. ► Deposited Ba preferentially attaches to Au herringbones, forming a stripe pattern. ► Ba can be oxidized by residual O due to its strong reactivity. ► Two well-ordered BaOx phases, a (6 × 6) and a (2√3 × 2√3)-R30° structure, coexist and lift the Au reconstruction.