Wurtzite structure in ultrathin ZnO films on Fe(110): Surface x-ray diffraction and <i>ab initio</i> calculations

Using surface x-ray diffraction in combination with ab initio calculations we have studied the atomic structure of ultra-thin ZnO films deposited on Fe(110). In contrast to expectation that ZnO adopts the "graphitic" hexagonal Boron-nitride structure to the Wurtzite (WZ) structure is observed. Its formation is related to oxygen impurities in Fe(110) hollow sites inducing an anisotropic charge redistribution within the film which is characterized by a metallic surface. Our results provide a deeper understanding of depolarization mechanisms in ultrathin polar films at the atomic scale.