Determination of the atomic structure of a Gd(1120) surface

Abstract

The atomic arrangement on a Gd(1120) surface has been determined by means of a quantitative low-energy electron diffraction (LEED) intensity analysis. The surface arrangement is found to be different from bulk structure in two ways: the spacing between the first and the second layer, both of which have two inequivalent atoms in the unit mesh, is contracted by 2.7% (0.05 AA), and the two inequivalent atoms in the first layer translate parallel to the surface by equal and opposite amounts of 0.10 AA. Thus the change in registration of the composite surface layer preserves both the size and the symmetry of the unit mesh of parallel bulk layers. This kind of surface rearrangement is a relaxation, and is very similar to the relaxation found on Tb(1120), but quite different from the reconstruction found by others on (1120) surfaces of some other rare-earth metals such as Y, Ho and Er.