Materials perspective on Casimir and van der Waals interactions

Abstract

Interactions induced by electromagnetic fluctuations, such as van der Waals and Casimir forces, are of universal nature present at any length scale between any types of systems with finite dimensions. Such interactions are important not only for the fundamental science of materials behavior, but also for the design and improvement of micro-and nano-structured devices. In the past decade, many new materials have become available, which has stimulated the need of understanding their dispersive interactions. The field of van der Waals and Casimir forces has experienced an impetus in terms of developing novel theoretical and computational methods to provide new insights in related phenomena. The understanding of such forces has far reaching consequences as it bridges concepts in materials, atomic and molecular physics, condensed matter physics, high energy physics, chemistry and biology. In this review, we summarize major breakthroughs and emphasize the common origin of van der Waals and Casimir interactions. We examine progress related to novel ab initio modeling approaches and their application in various systems, interactions in materials with Dirac-like spectra, force manipulations through nontrivial boundary conditions, and applications of van der Waals forces in organic and biological matter. The outlook of the review is to give the scientific community a materials perspective of van der Waals and Casimir phenomena and stimulate the development of experimental techniques and applications.

Casimir free energy of dielectric films: classical limit, low-temperature behavior and control

“…It is well known that there is an outstanding problem in the Lifshitz theory [2,3,6]. The point is that the low-frequency response of metals to classical electromagnetic fields is commonly described by the dissipative Drude model.…”

“…Thus, the fundamental theory of the van der Waals and Casimir forces (the Lifshitz theory) was originally formulated for two parallel semispaces separated by some distance a [1,2,24]. Later on, this theory was generalized for the cases of arbitrarily many plane parallel material layers and closely spaced surfaces of any geometrical shape [2,6].…”

“…The fluctuation-induced phenomena and, specifically, the van der Waals and Casimir forces, play a progressively increasing role in many topics of physics, chemistry and biology (see the monographs [1,2] and reviews [3,4,5,6]. They are responsible for interaction of electrically neutral, but polarizable, particles with material surfaces [7,8,9,10], find applications in nanoscience [11,12,13,14], play important role in many effects of condensed matter physics [15,16,17,18,19,20], and are even used in elementary particle physics for constraining some theoretical predictions beyond the standard model [21,22,23].…”

Interlayer electron–phonon coupling in WSe2/hBN heterostructures

“…Excitation spectroscopy reveals the double-resonance nature of such enhancement, and identifies the two resonant states to be the A exciton transition of monolayer WSe 2 and a new hybrid state present only in WSe 2 /hBN heterostructures. The observation of an interlayer electron-phonon interaction could open up new ways to engineer electrons and phonons for device applications.Van der Waals heterostructures of atomically thin twodimensional (2D) crystals are a new class of material in which novel quantum phenomena can emerge from layer-layer interactions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . For example, electron-electron interactions between adjacent 2D layers can give rise to a variety of fascinating physical behaviours: the interlayer moiré potential between the graphene and hBN layers leads to mini-Dirac cones and the Hofstadter's butterfly pattern in graphene/hBN heterostructures 5-10 ; electronic couplings between MoS 2 and MoS 2 layers lead to a direct-to indirect-bandgap transition in bilayer MoS 2 (refs 11,12); and Coulomb interactions between MoSe 2 and WSe 2 layers lead to interlayer exciton states in MoSe 2 /WSe 2 heterostructures 13,14 .…”

Numerical calculation of the Casimir-Polder interaction between a graphene sheet with vacancies and an atom

“…It is possible to tailor the sign and magnitude of dispersive forces by tuning, for example, the dielectric response of the plate. As a result, the correct modeling of dispersive forces from a materials science perspective becomes important [6,7].…”