Examinando por Autor "Woods, Lilia M."

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Casimir force phase transitions in the graphene family
(Springer Nature, 2017-03-15) Rodriguez-Lopez, Pablo; Kort-Kamp, Wilton J.M.; Dalvit, Diego A.R.; Woods, Lilia M.
The Casimir force is a universal interaction induced by electromagnetic quantum fluctuations between any types of objects. The expansion of the graphene family by adding silicene, germanene and stanene (2D allotropes of Si, Ge, and Sn), lends itself as a platform to probe Dirac-like physics in honeycomb staggered systems in such a ubiquitous interaction. We discover Casimir force phase transitions between these staggered 2D materials induced by the complex interplay between Dirac physics, spin-orbit coupling and externally applied fields. In particular, we find that the interaction energy experiences different power law distance decays, magnitudes and dependences on characteristic physical constants. Furthermore, due to the topological properties of these materials, repulsive and quantized Casimir interactions become possible.
Confinement-Induced Nonlocality and Casimir Force in Transdimensional Systems
(The Royal Society of Chemistry, 2023-10-09) Bondarev, Igor V.; Pugh, Michael D.; Rodriguez-Lopez, Pablo; Woods, Lilia M.; Antezza, Mauro
We study within the framework of the Lifshitz theory the long-range Casimir force for in-plane isotropic and anisotropic free-standing transdimensional material slabs. In the former case{,} we show that the confinement-induced nonlocality not only weakens the attraction of ultrathin slabs but also changes the distance dependence of the material-dependent correction to the Casimir force to go as contrary to the ∼1/l dependence of that of the local Lifshitz force. In the latter case{,} we use closely packed array of parallel aligned single-wall carbon nanotubes in a dielectric layer of finite thickness to demonstrate strong orientational anisotropy and crossover behavior for the inter-slab attractive force in addition to its reduction with decreasing slab thickness. We give physical insight as to why such a pair of ultrathin slabs prefers to stick together in the perpendicularly oriented manner{,} rather than in the parallel relative orientation as one would customarily expect.
Giant anisotropy and Casimir phenomena: The case of carbon nanotube metasurfaces
(American Physical Society, 2024-01-17) Rodriguez-Lopez, Pablo; Le, Dai-Nam; Bondarev, Igor V.; Antezza, Mauro; Woods, Lilia M.
The Casimir interaction and torque are related phenomena originating from the exchange of electromagnetic excitations between objects. While the Casimir force exists between any types of objects, the materials or geometrical anisotropy drives the emergence of the Casimir torque. Here both phenomena are studied theoretically between dielectric films with immersed parallel single wall carbon nanotubes in the dilute limit with their chirality and collective electronic and optical response properties taken into account. It is found that the Casimir interaction is dominated by thermal fluctuations at sub-micron separations, while the torque is primarily determined by quantum mechanical effects. This peculiar quantum vs. thermal separation is attributed to the strong influence of reduced dimensionality and inherent anisotropy of the materials. Our study suggests that nanostructured anisotropic materials can serve as novel platforms to uncover new functionalities in ubiquitous Casimir phenomena.
Phonon-assisted Casimir interactions between piezoelectric materials
(Nature Portfolio, 2024-12-02) Le, Dai-Nam; Rodriguez-Lopez, Pablo; Woods, Lilia M.
The strong coupling between electromagnetic fields and lattice oscillations in piezoelectric materials gives rise to phonon polariton excitations. Such quasiparticles are important in modulating the ubiquitous Casimir force. Here by utilizing the generalized Born-Huang hydrodynamics model exemplified in SiC, three types of phonons are studied: longitudinal optical phonon, transverse optical phonon and phonon polariton. The Fresnel reflection coefficients for the piezoelectric composed of semi-infinite substrates or thin films are then obtained by taking into account the phonon-electromagnetic coupling. The Casimir interaction, calculated via a generalized Lifshitz approach, is examined to highlight the interplay between different types of phonon modes and electromagnetic excitations. Our study shows that piezoelectrics emerge as materials where this ubiquitous force can be controlled via phonon properties. Different types of surface phonon polaritons associated with structural polytypes may also be distinguished through the Casimir interaction.