Photoinduced Enhancement of the Charge Density Wave Amplitude
Photoinduced Enhancement of the Charge Density Wave Amplitude
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DOI：
10.1103/physrevlett.117.056401
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发表时间：
2016-07-25
影响因子：
8.6
通讯作者：
Shpyrko, O. G.
中科院分区：
文献类型：
--
作者：
Singer, A.;Patel, S. K. K.;Shpyrko, O. G.
对称性破缺和有序的出现是凝聚态物理中最令人着迷的现象之一。它导致了在反铁磁体、莫特绝缘体、超导体和密度波系统中发现的大量有趣的基态。利用远离平衡的物质状态可以提供更惊人的途径，使其达到更低的有序状态。在这里，我们证明了元素铬的情况下，温和的超快光激发可以瞬时提高电荷密度波（CDW）的振幅高达30%以上的平衡值，而强激发导致振荡，大振幅CDW状态，持续高于平衡转变温度。这两种效应都是由动态的电子-声子相互作用引起的，提供了一种有效的机制来选择性地将电子顺序的宽激发转化为定义明确的、长寿命的相干晶格振动。这种机制可以被利用来瞬时增强其他系统的序参数与耦合自由度。
Symmetry breaking and the emergence of order is one of the most fascinating phenomena in condensed matter physics. It leads to a plethora of intriguing ground states found in antiferromagnets, Mott insulators, superconductors, and density-wave systems. Exploiting states of matter far from equilibrium can provide even more striking routes to symmetry-lowered, ordered states. Here, we demonstrate for the case of elemental chromium that moderate ultrafast photoexcitation can transiently enhance the charge-density-wave (CDW) amplitude by up to 30% above its equilibrium value, while strong excitations lead to an oscillating, large-amplitude CDW state that persists above the equilibrium transition temperature. Both effects result from dynamic electron-phonon interactions, providing an efficient mechanism to selectively transform a broad excitation of the electronic order into a well-defined, long-lived coherent lattice vibration. This mechanism may be exploited to transiently enhance order parameters in other systems with coupled degrees of freedom.