  Surface corrugation functions, derived from elastic helium atom scattering
(HAS) diffraction patterns at different temperatures, reveal that the Cu2+ rows
in the (001) surface of LiCu2O2 undergo an outward displacement of about 0.15
{\AA} as the surface was cooled down to 140 K. This is probably the first time
that isolated one-dimensional magnetic ion arrays were realized, which
qualifies the Li1+Cu2+O2-2 surface as a candidate to study one-dimensional
magnetism. The rising Cu2+ rows induce a surface incommensurate structural
transition along the a-direction. Surface equilibrium analysis showed that the
surface Cu2+ ions at bulk-like positions experience a net outward force along
the surface normal which is relieved by the displacement. Temperature-dependent
changes of the surface phonon dispersions obtained with the aid of inelastic
HAS measurements combined with surface lattice dynamical calculations are also
reported.
