We report active control of the friction force at the contact between a nanoscale asperity and a ${\mathrm{La}}_{0.55}{\mathrm{Ca}}_{0.45}\mathrm{Mn}{\mathrm{O}}_3$ (LCMO) thin film using electric fields. We use friction force microscopy under ultrahigh vacuum conditions to measure the friction force as we change the film resistive state by electric-field-induced resistive switching. Friction forces are high in the insulating state and clearly change to lower values when the probed local region is switched to the conducting state. Upon switching back to an insulating state, the friction forces increase again. Thus we demonstrate active control of friction without having to change the contact temperature or pressure. By comparing with measurements of friction at the metal-to-insulator transition and with the effect of applied voltage on adhesion, we rule out electronic excitations, electrostatic forces, and changes in contact area as the reasons for the effect of resistive switching on friction. Instead, we argue that friction is limited by phonon relaxation times, which are strongly coupled to the electronic degrees of freedom through distortions of the $\mathrm{Mn}{\mathrm{O}}_6$ octahedra. The concept of controlling friction forces by electric fields should be applicable to any materials where the field produces strong changes in phonon lifetimes.

中文翻译：

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使用电场切换锰矿表面的摩擦

我们报告主动控制纳米级粗糙和表面之间的接触摩擦力。 ${啦}_{0.55}{钙}_{0.45}锰{\mathrm{Ø}}_3$（LCMO）薄膜使用电场。我们通过在超高真空条件下使用摩擦力显微镜来测量摩擦力，因为我们通过电场感应的电阻切换来改变薄膜的电阻状态。在绝缘状态下，摩擦力较高，并且在将探测到的局部区域切换为导电状态时，摩擦力会明显减小。在切换回绝缘状态时，摩擦力再次增加。因此，我们展示了在不改变接触温度或压力的情况下主动控制摩擦的方法。通过与金属到绝缘体过渡处的摩擦测量结果以及施加的电压对附着力的影响进行比较，我们排除了电子激励，静电力和接触面积的变化，这是电阻切换对摩擦产生影响的原因。代替，$锰{\mathrm{Ø}}_6$八面体。通过电场控制摩擦力的概念应适用于电场在声子寿命方面产生很大变化的任何材料。