Stripe and Short Range Order in the Charge Density Wave of 1T-CuxTiSe2
Stripe and Short Range Order in the Charge Density Wave of 1T-CuxTiSe2
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DOI：
10.1103/physrevlett.118.017002
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发表时间：
2017-01-03
影响因子：
8.6
通讯作者：
Renner, Ch.
中科院分区：
文献类型：
--
作者：
Novello, A. M.;Spera, M.;Renner, Ch.
我们通过扫描隧道显微镜和光谱研究了 Cu 插层对 1T-CuxTiSe2 中电荷密度波 (CDW) 的影响。通过密度泛函理论模型识别的铜原子被发现随机嵌入在范德华间隙的八面体位点上，并在费米能级附近掺杂离域电子。虽然 CDW 调制周期不取决于 Cu 含量，但我们观察到在低 Cu 含量 (x < 0.02) 下形成电荷条纹域，并在较高 Cu 含量下将相应的顺序分解为 2 x 2 域。后者随着铜浓度的增加而收缩，并且倾向于发生相移。这些发现使得激子配对作为该材料中主要 CDW 形成机制的提议无效。
We study the impact of Cu intercalation on the charge density wave (CDW) in 1T-CuxTiSe2 by scanning tunneling microscopy and spectroscopy. Cu atoms, identified through density functional theory modeling, are found to intercalate randomly on the octahedral site in the van der Waals gap and to dope delocalized electrons near the Fermi level. While the CDW modulation period does not depend on Cu content, we observe the formation of charge stripe domains at low Cu content (x < 0.02) and a breaking up of the commensurate order into 2 x 2 domains at higher Cu content. The latter shrink with increasing Cu concentration and tend to be phase shifted. These findings invalidate a proposed excitonic pairing as the primary CDW formation mechanism in this material.