Saint-Paul M, Dumas J, Marcus J
Institut Néel, CNRS/UJF, BP 166, F-38042 Grenoble Cedex 9, France.
J Phys Condens Matter. 2009 May 27;21(21):215603. doi: 10.1088/0953-8984/21/21/215603. Epub 2009 Apr 24.
The charge density wave (CDW) nonlinear conductivity of the blue bronzes A(0.30)MoO(3) (A = K, Rb) shows two different regimes depending on the temperature: a strongly damped CDW motion above ∼50 K and a CDW motion with almost no damping below ∼50 K. In a search for an elastic signature of this CDW behaviour, we performed ultrasonic measurements on A(0.30)MoO(3) single crystals in the temperature range 4-300 K. In Rb(0.30)MoO(3), at T∼50 K, upon cooling, a large increase of the sound velocity for the longitudinal mode measured along the [Formula: see text], [102] and b directions is observed. The ultrasonic attenuation coefficient shows an increase down to 50 K followed by a plateau. Similar results are found in K(0.30)MoO(3). In V-doped samples, Rb(0.30)(Mo(1-x)V(x))O(3) (x = 0.4%) the anomaly broadens and is shifted towards higher temperatures. The results are discussed in relation to the changes in the CDW rigidity, disorder and dielectric response. A scenario based on a glass transition for the CDW superstructure is proposed.
蓝色青铜A(0.30)MoO(3)（A = K、Rb）的电荷密度波（CDW）非线性电导率根据温度表现出两种不同状态：在约50K以上为强阻尼CDW运动，在约50K以下为几乎无阻尼的CDW运动。为了寻找这种CDW行为的弹性特征，我们在4 - 300K温度范围内对A(0.30)MoO(3)单晶进行了超声测量。在Rb(0.30)MoO(3)中，在T约为50K时，冷却过程中，观察到沿[公式：见正文]、[102]和b方向测量的纵向模式声速大幅增加。超声衰减系数在降至50K之前增加，之后趋于平稳。在K(0.30)MoO(3)中也发现了类似结果。在V掺杂样品Rb(0.30)(Mo(1 - x)V(x))O(3)（x = 0.4%）中，异常变宽并向更高温度移动。结合CDW刚度、无序度和介电响应的变化对结果进行了讨论。提出了一种基于CDW超结构玻璃化转变的设想。
