Stable reconstruction of the polar (111) surface of NiO on Au(111)

Several theoretical studies of the stability of (111)-terminated ionic crystals with the NaCl structure have predicted that the crystal Madelung energy can be stabilized by a simple surface reconstruction. However, previous attempts to grow (111)-terminated crystals have resulted in either unreconstructed or faceted surfaces. We demonstrate that deposition of Ni in an oxygen atmosphere onto a Au(111) substrate held at T{~}300 ^∘{}C results in the growth of a stable p(2×{}2) reconstructed NiO(111) and resolve the atomic details of this surface with our scanning tunneling microscope.