Repulsive Casimir force between silicon dioxide and superconductor

Abstract

The Casimir force, one of the most relevant causes of stiction problems, gives rise to critical impediments in the fabrication and operation of nano/micro-electromechanical systems (NEMS/MEMS). In almost all cases in which the scale is of hundreds of nanometers, Casimir interactions produce such significant amount of friction as to attract the attention of scientists from a wide variety of research fields [1 -3]. The theoretical understanding and measurements of Casimir interactions have advanced substantially in the last ten years, allowing physicists to have a more detailed understanding of the fundamental physics, not only in nanophysics, but particle physics and cosmology as well.The simplest Casimir system was generated theoretically by Casimir in 1948 when he developed a model describing the interaction between two parallel conducting plates [4]. Since then, the Casimir forces between real materials such as metals [5], semiconductors [6], semimetals [7] and high-T c superconductors [8] have been extensively studied theoretically and experimentally. It has been found that the presence of liquids between two objects allows the sign of the Casimir force to switch [1 -3]. These repulsive Casimir forces appear when the dielectric functions of object 1 and object 2 immersed in a medium 3 satisfy the relation 1ε ξ ε ξ ε ξ over a wide imaginary frequency range . ξ It is also possible to achieve the repulsion using arrays of gold nanopillars on two plates [9]. In addition, metamaterials are promising candidates for creating these repulsive interactions [10]. The combination between experimental measurements and theoretical calculations has provided essential information to help researchers design nanoscale devices.The well-known Lifshitz theory developed a generalization of the Casimir force [3,11,13]. In the theory, the force between uncharged objects made of real materials is given by an analytical formula with frequency-dependent dielectric permittivity ( ). i ε ξ Variation of the dielectric functions causes the change of the Casimir interactions. The Casimir-Lifshitz force has been studied for systems at the thermal equilibrium in atom-atom, plane-plane and atom-plane configurations [11,12]. Cuprate superconductors, high-T c superconductors and anisotropic materials are widely used in various devices. It has been shown theoretically that the Casimir force in the BSCCO-air-gold system is significantly affected by the anisotropy in the dielectric functions. In the present Letter, the Casimir -Lifshitz force is calculated in the case of a perpendicular cleave between cuprate superconductor and silica with bromobenzene in between. The calculation of the force takes into account the thermal effect and the influence of thickness on the dispersion force. The force is repulsive and is associated with the sticking process in nanodevices.The general expression describing the Casimir interaction between two infinite parallel plates is the Lifshitz formula. At a given separation a and given temperature T, the Casimir press...

Interaction of a graphene sheet with a ferromagnetic metal plate

“…The Casimir interaction originates from the quantum electromagnetic fluctuations between two objects [2,3,6]. It provides a fundamental understanding about nanoscience and has a significant influence on the high performance of devices.…”

Van der Waals interactions between graphitic nanowiggles

“…This calculation, however, considers only the pairwise interaction between two atoms and ignores the effects induced by other atoms. Another approach is built up from the Lifshitz theory [10][11][12]. This theory allows us to calculate the van der Waals and Casimir force between two parallel semi-infinite plates using dielectric functions of objects as a function of the imaginary frequency.…”