Liberal Olleta, Íñigo

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Liberal Olleta

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Íñigo

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Ingeniería Eléctrica, Electrónica y de Comunicación

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ISC. Institute of Smart Cities

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Now showing 1 - 2 of 2
  • PublicationOpen Access
    Electrically switchable Casimir forces using transparent conductive oxides
    (American Physical Society, 2022) Gong, Tao; Spreng, Benjamin; Camacho, Miguel; Liberal Olleta, Íñigo; Engheta, Nader; Munday, Jeremy N.; Institute of Smart Cities - ISC
    Casimir forces between charge-neutral bodies originate from quantum vacuum fluctuations of electromagnetic fields, which exhibit a critical dependence on material's electromagnetic properties. Over the years, in situ modulation of a material's optical properties has been enabled through various means and has been widely exploited in a plethora of applications such as electro-optical modulation, transient color generation, bio- or chemical sensing, etc. Yet Casimir force modulation has been hindered by difficulty in achieving high modulation signals due to the broadband nature of the Casimir interaction. Here we propose and investigate two configurations that allow for in situ modulation of Casimir forces through electrical gating of a metal-insulator-semiconductor junction comprised of transparent conductive oxide (TCO) materials. By switching the gate voltage on and off, a force modulation of >400 pN is predicted due to substantive charge carrier accumulation in the TCO layer, which can be easily measured using state-of-the-art force measurement techniques in an atomic force microscope. We further examine the influence of the oxide layer thickness on the force modulation, suggesting the importance of the fine control of the oxide layer deposition. Our work provides a promising pathway for modulating the Casimir effect in situ with experimentally measurable force contrast.
  • PublicationOpen Access
    Effect of epsilon-near-zero modes on the casimir interaction between ultrathin films
    (American Physical Society, 2023) Gong, Tao; Liberal Olleta, Íñigo; Spreng, Benjamin; Camacho, Miguel; Engheta, Nader; Munday, Jeremy N.; Institute of Smart Cities - ISC
    Vacuum fluctuation-induced interactions between macroscopic metallic objects result in an attractive force between them, a phenomenon known as the Casimir effect. This force is the result of both plasmonic and photonic modes. For very thin films, field penetration through the films will modify the allowed modes. Here, we theoretically investigate the Casimir interaction between ultrathin films from the perspective of force distribution over real frequencies for the first time. Pronounced repulsive contributions to the force are found due to the highly confined and nearly dispersion-free epsilon-near-zero (ENZ) modes that only exist in ultrathin films. These contributions persistently occur around the ENZ frequency of the film irrespective of the interfilm separation. We further associate the ENZ modes with a striking thickness dependence of a proposed figure of merit (FOM) for conductive thin films, suggesting that the motion of objects induced by Casimir interactions is boosted for deeply nanoscale sizes. Our results shed light on the correlation between special electromagnetic modes and the vacuum fluctuation-induced force as well as the resulting mechanical properties of ultrathin ENZ materials, which may create new opportunities for engineering the motion of ultrasmall objects in nanomechanical systems.