Emergence of coherence in the charge-density wave state of 2H-NbSe2.
Emergence of coherence in the charge-density wave state of 2H-NbSe2.
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DOI：
10.1038/ncomms7313
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发表时间：
2015-02-17
影响因子：
16.6
通讯作者：
Rosenkranz, S.
中科院分区：
文献类型：
--
作者：
Chatterjee, U.;Zhao, J.;Iavarone, M.;Di Capua, R.;Castellan, J. P.;Karapetrov, G.;Malliakas, C. D.;Kanatzidis, M. G.;Claus, H.;Ruff, J. P. C.;Weber, F.;van Wezel, J.;Campuzano, J. C.;Osborn, R.;Randeria, M.;Trivedi, N.;Norman, M. R.;Rosenkranz, S.
电荷密度波（CDW）的状态具有由具有振幅和相位的复序参数描述的破缺对称性。基于清洁、弱耦合系统的传统观点是，在CDW转变温度Tcdw时，有限振幅和远程相位相干性同时出现。本文利用光电发射、x射线散射和扫描隧道显微镜研究了典型的CDW化合物2H-NbSe2嵌入Mn和Co，并表明传统的观点是站不住脚的。我们发现，无论是在高温下还是在大插层下，CDW阶变短，振幅明确，这对电子色散有影响，产生能隙。Tcdw的相变标志着具有全局相相干性的长程序的开始，导致剧烈的电子激发。我们的观察结果强调了强耦合CDW系统中相位波动的重要性，并提供了对“伪间隙”状态中相位不相干的重要性的见解。电荷密度波用复阶参数来描述，其振幅在转变温度下消失。研究表明，2H-NbSe2的相变是由有序参数的相位波动驱动的，在无序状态下存在有限的振幅。
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature Tcdw. Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at Tcdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states. Charge density waves are described by a complex order parameter whose amplitude is expected to vanish at the transition temperature. This study shows that the transition in 2H-NbSe2 is driven by fluctuations of the phase of the order parameter, with a finite amplitude surviving in the disordered state.
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DOI：
10.1073/pnas.1101008108
发表时间：
2011-06-07
影响因子：
11.1
作者：
Chatterjee, Utpal;Ai, Dingfei;Campuzano, J. C.
通讯作者：
Campuzano, J. C.
影响因子：
3.7
作者：
MUTKA, H;ZUPPIROLI, L;BOURGOIN, JC
通讯作者：
BOURGOIN, JC
影响因子：
8.6
作者：
Matsui, H;Sato, T;Matsuda, A
通讯作者：
Matsuda, A
影响因子：
19.6
作者：
Bouadim, Karim;Loh, Yen Lee;Trivedi, Nandini
通讯作者：
Trivedi, Nandini
影响因子：
3.7
作者：
MCMILLAN, WL
通讯作者：
MCMILLAN, WL