Precursor of photoinduced structural phase transitions in a coupled-chain system with an electron-lattice interaction
Precursor of photoinduced structural phase transitions in a coupled-chain system with an electron-lattice interaction
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具有电子-晶格相互作用的耦合链系统中光致结构相变的前体
DOI：
10.1103/physrevb.65.024302
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发表时间：
2001
影响因子：
3.7
通讯作者：
K. Iwano
中科院分区：
文献类型：
--
作者：
K. Iwano
与电子晶格相互作用的耦合链系统中讨论了光诱导的结构相变（PSPT）的前体。在这里，我们假设一个具有电荷密度波（CDW）基态的系统是照相。由于选择电子带填充仅为一半，因此我们有两个CDW阶段。我们通过依赖站点的能量术语来提高他们的退化，以准备稳定和亚稳态的相位，然后研究从前者到后者的光转换。选择合适的参数集，我们获得了一种情况，即通过在小空间区域中多达四种单电子激发的聚集形成前体。聚集的驱动力是两种单电子激发与两种两电子激发之间的有吸引力的相互作用。有人强调的是，前体具有一个一维域的结构，并夹在两个域壁之间。另一方面，在较少的电子兴奋剂的情况下，我们只观察到局部照片放宽状态，该状态既不与域或域壁有关。在最低四电子激发的电势表面上，这两个状态共存。因此，我们使用半古典计算从稳定性的角度直接比较它们。结果，我们可以安全地得出结论，相对于辐射和非放射性衰减通道，前者比后者更具稳定器。
A precursor of photoinduced structural phase transitions (PSPTs) is discussed in a coupled-chain system with an electron-lattice interaction. Here, we assume that a system with a charge-density-wave (CDW) ground state is photo-excited. Since the electron band-filling is chosen to be just half, we have two CDW phases. We lift their degeneracy by a site-dependent energy term to prepare stable and metastable phases, and then study the photo-conversion from the former to the latter. Choosing a suitable parameter set, we obtain a situation where a precursor is formed via the aggregation of as many as four one-electron excitations in a small spatial region. The driving force for the aggregation is an attractive interaction between two one-electron excitations and between two two-electron excitations. It is emphasized that the precursor has a structure of a one-dimensional domain, being sandwiched between two domain walls. In the case of fewer electron-excitations, on the other hand, we only observe a locally photo-relaxed state, which is associated with neither a domain nor a domain wall. On the potential surface for the lowest four-electron excitation, these two states coexist. Thus, we directly compare them from the viewpoint of stability, using semi-classical calculations. As a result, we safely conclude that the former is much stabler than the latter with respect to both radiative and nonradiative decay channels.