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arXiv 1209.5848cond-mat.mes-hall
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MEMS中的Casimir吸引-排斥跃迁

Casimir attractive-repulsive transition in MEMS

M. Boström, S. Å. Ellingsen, I. Brevik, M. Dou, C. Persson, Bo E. Sernelius

摘要:

由于色散(范德华力或卡西米尔力)导致的微机械和纳米机械(NEMS/MEMS)系统中的不需要的静摩擦是制造具有这些长度尺度上的移动部件的系统的显著障碍。在物体之间的间隙中引入适当的介电液体之前已经证明使色散力排斥,或者甚至作为分离的函数切换符号。利用最近可用的介电常数的数据计算我们表明,这样一个显着的非单调Casimir力,从吸引力到排斥力的分离增加,实际上可以观察到在系统中的组成材料是在标准的NEMS/MEMS使用不需要特殊或外来的材料。迄今为止,还没有测量到这种非单调行为。我们计算的力之间的二氧化硅球和一个平面的氧化锌或氧化铝,这两种材料是最突出的实际微电子和微光学器件。我们的研究结果解释了需要高度准确的介电常数函数的材料所涉及的频率从光学到远红外频率。Casimir相互作用的仔细分析,我们展示了如何在相互作用的符号的变化可以理解为一个给定的设置中涉及的三种介质的介电函数的多个交叉的结果。

英文摘要:

Unwanted stiction in micro- and nanomechanical (NEMS/MEMS) systems due to dispersion (van der Waals, or Casimir) forces is a significant hurdle in the fabrication of systems with moving parts on these length scales. Introducing a suitably dielectric liquid in the interspace between bodies has previously been demonstrated to render dispersion forces repulsive, or even to switch sign as a function of separation. Making use of recently available permittivity data calculated by us we show that such a remarkable non-monotonic Casimir force, changing from attractive to repulsive as separation increases, can in fact be observed in systems where constituent materials are in standard NEMS/MEMS use requiring no special or exotic materials. No such nonmonotonic behaviour has been measured to date. We calculate the force between a silica sphere and a flat surface of either zinc oxide or hafnia, two materials which are among the most prominent for practical microelectrical and microoptical devices. Our results explicate the need for highly accurate permittivity functions of the materials involved for frequencies from optical to far-infrared frequencies. A careful analysis of the Casimir interaction is presented, and we show how the change in the sign of the interaction can be understood as a result of multiple crossings of the dielectric functions of the three media involved in a given set-up.

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