Friction anomalies at first-order transition spinodals: 1T-TaS2
Friction anomalies at first-order transition spinodals: 1T-TaS2
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DOI：
10.1088/1367-2630/aaac00
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发表时间：
2018-02-15
影响因子：
3.3
通讯作者：
Tosatti, Erio
中科院分区：
文献类型：
--
作者：
Panizon, Emanuele;Marx, Torben;Tosatti, Erio
通过纳米尖端在其表面滑动的摩擦力的机械异常来揭示固体的相变，这是一种成功的连续相变方法，但对于一阶相变来说仍然是一种尚未探索的工具。由于缓慢成核，一级结构转变伴随着滞后发生，包括在两个旋节线温度之间，在热力学转变的两侧，一个或另一个亚稳态自由能分支终止。旋节线转变是一种不存在热容异常的集体一次性事件，很容易被微弱的外部扰动触发。在这里，我们表明，即使是 AFM 尖端的游丝机械作用也可以局部充当触发器，勉强抢占自发旋节线变换，并使其作为纳米摩擦异常可观察到。重要层状化合物 1T-TaS2 的 CCDW-NCCDW 一级跃迁证实了这一预期，从而证明了这种效应。
Revealing phase transitions of solids through mechanical anomalies in the friction of nanotips sliding on their surfaces, a successful approach for continuous transitions, is still an unexplored tool for first-order ones. Owing to slow nucleation, first-order structural transformations occur with hysteresis, comprised between two spinodal temperatures where, on both sides of the thermodynamic transition, one or the other metastable free energy branches terminates. The spinodal transformation, a collective one-shot event without heat capacity anomaly, is easy to trigger by a weak external perturbation. Here we show that even the gossamer mechanical action of an AFM-tip can locally act as a trigger, narrowly preempting the spontaneous spinodal transformation, and making it observable as a nanofrictional anomaly. Confirming this expectation, the CCDW-NCCDW first-order transition of the important layer compound 1T-TaS2 is shown to provide a demonstration of this effect.