Temperature-dependent anomalies in the structure of the (001) surface of LiCu2O2

SURFACE SCIENCE

卷:605

Article

Zhu, Xuetao¹  Yao, Yangyang¹  Hsu, H. C.²  Chou, F. C.²  El-Batanouny, M.¹ 

[1] Boston Univ, Dept Phys, Boston, MA 02215 USA

[2] Natl Taiwan Univ, Ctr Condensed Matter Sci, Taipei 10617, Taiwan

关键词: LiCu2O2;    Surface incommensurate phase transition;    One-dimensional magnetism;    Helium atom scattering;    Surface structure;    Surface dynamics;    Surface phonons;   

DOI  :  10.1016/j.susc.2010.11.004

来源: Elsevier

【 摘 要 】

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 angstrom as the surface was cooled down to 140 K. This raises the possibility that isolated one-dimensional magnetic ion arrays may be realized; if true, it qualifies the Li-1 (+) Cu-2 (+) O-2(2-) surface as a candidate to study one-dimensional magnetism. The rising Cu2+ rows induce a thermally activated 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, consistent with the rise of the Cu2+ rows, obtained with the aid of inelastic HAS measurements combined with surface lattice dynamical calculations are also reported. (C) 2010 Elsevier B.V. All rights reserved.

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