Figure 1

Formation of reconstructed phases on the annealed $\text{Cu}\left(110\right)\text{−}\left(2\times 1\right)\text{-O}$ surface. (a) STM topography ($U_{\text{bias}}=-1.2\text{V}$, $I_t=0.5\text{nA}$) of the $\text{Cu}\left(110\right)\text{−}\left(2\times 1\right)\text{-O}$ surface annealed at $500°\text{C}$ for 30 min. The step bunches separating the terraces $\left(T_1\text{−}{T}_4\right)$ are marked by arrows. The surface dislocations are denoted as $A$, $B$, and $C$. The black lines depict STM height profiles taken in vicinity of the dislocations. (b) STM topography of the surface area around the $A$ and $B$ dislocations. The $\left(2\times 1\right)\text{-O}$ strips running in [001] direction are clearly visible. The dislocation-induced surface steps and the corresponding splitting points are denoted as $S_A$, $S_B$, and $I_A$, $I_B$, respectively. (c) The area of the phases (hatched bars) as a function of the surface curvature in vicinity of the $A$, $B$, and $C$ dislocations. The curvature of the $T_2$ terrace and the zero curvature of a flat surface (dotted line) are indicated for comparison. (d) STM height profiles used in (c) to determine the surface curvatures.Reuse & Permissions

Figure 2

Structural analysis of the $A$ phase. (a) STM topography of the $A$ phase. Two distinct phases, $A_1$ and $A_2$, constituting the $A$ phase are marked consequently. (b) STM topography of the $A_1$ phase. The chains are regularly spaced in the $\left[1\overline{1}0\right]$ direction with the $\times 4$ periodicity, the $\times 1$ shift of each second chain in the [001] direction reveals the $c\left(8\times 2\right)$ unit cell which is specified by the black-and-white lines. (c) STM topography of the $A_2$ phase: a two-dimensional array of Cu-O clusters ordered in the $\left[5\overline{5}2\right]$ and $\left[3\overline{3}\overline{2}\right]$ directions, the corresponding $\left[\frac{5}{2}\frac{2}{\overline{2}}\right]$ unit cell is specified. In inset: the single cluster containing four Cu atoms (marked by arrows). The bright roundlike protrusions are the Cu adatoms randomly adsorbed on top of the clusters and screening their characteristic butterflylike shape. (d) Schematics of the $\left(2\times 1\right)\text{-O}$ phase. The white grid lines represent the close-packed rows of the Cu substrate. The O and Cu atoms of the $\left(2\times 1\right)\text{-O}$ phase are shown as gray and white circles, respectively. The $\left(2\times 1\right)$ unit cell is specified by the black-and-white lines. (e)–(f) Structural models of the (e) $A_1$ phase and (f) $A_2$ phase. The Cu adatoms on (f) are shown as white circles of larger size, the O-Cu-O chain fragment is marked by arrow, the ${\text{Cu}}_4{\text{O}}_8$ cluster is highlighted. The strain of the Cu lattice underlying the $A_1$ and $A_2$ phases is shown schematically at the upper-right corner of each model. The arrows designate the strain direction, the values represent the compression of the Cu lattice (in percents to the nominal lattice parameter) measured in the [001] and $\left[1\overline{1}0\right]$ directions. (g)–(h) Matching the structural models, shown on (e) and (f), with the corresponding STM topographies, shown in (b) and (c).Reuse & Permissions