ARPES Line Shapes in FL and non-FL Quasi-Low-Dimensional Inorganic Metals

G. -H. Gweon; J. D. Denlinger; J. W. Allen; R. Claessen; C. G. Olson; H. Hoechst; J. Marcus; C. Schlenker; L. F. Schneemeyer

paper

ARPES Line Shapes in FL and non-FL Quasi-Low-Dimensional Inorganic Metals

arXiv:cond-mat/0103470

Abstract

Quasi-low-dimensional (quasi-low-D) inorganic materials are not only ideally suited for angle resolved photoemission spectroscopy (ARPES) but also they offer a rich ground for studying key concepts for the emerging paradigm of non-Fermi liquid (non-FL) physics. In this article, we discuss the ARPES technique applied to three quasi-low-D inorganic metals: a paradigm Fermi liquid (FL) material TiTe $_{2}$ , a well-known quasi-1D charge density wave (CDW) material K $_{0.3}$ MoO $_{3}$ and a quasi-1D non-CDW material Li $_{0.9}$ Mo $_{6}$ O $_{17}$ . With TiTe $_{2}$ , we establish that a many body theoretical interpretation of the ARPES line shape is possible. We also address the fundamental question of how to accurately determine the {\bf k} $_{F}$ value from ARPES. Both K $_{0.3}$ MoO $_{3}$ and Li $_{0.9}$ Mo $_{6}$ O $_{17}$ show quasi-1D electronic structures with non-FL line shapes. A CDW gap opening is observed for K $_{0.3}$ MoO $_{3}$ , whereas no gap is observed for Li $_{0.9}$ Mo $_{6}$ O $_{17}$ . We show, however, that the standard CDW theory, even with strong fluctuations, is not sufficient to describe the non-FL line shapes of K $_{0.3}$ MoO $_{3}$ . We argue that a Luttinger liquid (LL) model is relevant for both bronzes, but also point out difficulties encountered in comparing data with theory. We interpret this situation to mean that a more complete and realistic theory is necessary to understand these data.

23 pages, including 21 figures; to appear in a special issue of J. Elec. Spectr. Rel. Phenom