Casimir Force Measurements Between Metal and High-Tc Superconductor Surfaces (original) (raw)
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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • Tuning of cut off frequency in ternary superconducting PC has been investigated. • Cut off frequency can be alter by the use of different combination of superconductor materials. • The structure can act as high pass filter, reflector etc.
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In this paper, we have theoretically investigated the optical spectra of all superconducting aperiodic photonic crystals comprising from different superconductors namely high-high, low-low and high-low temperature configurations. Also, the name Octonacci is composed of Octo-from octagonal and-acci from the Fibonacci sequence, however, the Octonacci sequence has a geometric origin. In order to show the difference between TE-and TM-polarized lightwaves, we have analyzed both the influence of the incident angle and temperature of light wave on the PBGs as well as transmittance resonance-peaks. By the way, the possibility of obtaining deep photonic band gap (PBG) has been provided for both TE and TM polarizations for the most incident angles. This study also investigates the effect of generation number of the Octonacci sequence on the PBG spectrum within the visible range. The results show that optical performances of Octonacci all superconducting aperiodic photonic crystals are higher than Fibonacci ones even with upper generations. Finally, to show the impact of the results, we have made a comparison between this new investigating quasi-periodic sequence and periodic all superconducting ones.
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The design-properties of one-dimensional photonic quasicrystals (PQC) are studied in a microwave frequency range using the transfer matrix method (TMM) and Gorter Casimir Two-Fluid Model (GCTM). The PQC is constructed by a dielectric (SiO 2) and High Tc superconducting BSCCO (Bi 2 Sr 2 CaCu 2 O 8) materials and organized following the Generalized Fibonacci class (GFC). We have shown that similar channels with zero transmission easily controlled by the order and the lattice parameters of quasiperiodic systems. The cutoff frequency of the opened central gap found at specific arrangement (m = n) is adjusted with changing the temperature and layer thickness of superconductor. The main heterostructure can be useful to design a gigahertz multi channeled filter with similar channels.
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Pseudogap from ARPES experiment: three gaps in cuprates and topological superconductivity
A term first coined by Mott back in 1968 a `pseudogap' is the depletion of the electronic density of states at the Fermi level, and pseudogaps have been observed in many systems. However, since the discovery of the high temperature superconductors (HTSC) in 1986, the central role attributed to the pseudogap in these systems has meant that by many researchers now associate the term pseudogap exclusively with the HTSC phenomenon. Recently, the problem has got a lot of new attention with the rediscovery of two distinct energy scales (`two-gap scenario') and charge density waves patterns in the cuprates. Despite many excellent reviews on the pseudogap phenomenon in HTSC, published from its very discovery up to now, the mechanism of the pseudogap and its relation to superconductivity are still open questions. The present review represents a contribution dealing with the pseudogap, focusing on results from angle resolved photoemission spectroscopy (ARPES) and ends up with the conclusion that the pseudogap in cuprates is a complex phenomenon which includes at least three different `intertwined' orders: spin and charge density waves and preformed pairs, which appears in different parts of the phase diagram. The density waves in cuprates are competing to superconductivity for the electronic states but, on the other hand, should drive the electronic structure to vicinity of Lifshitz transition, that could be a key similarity between the superconducting cuprates and iron based superconductors. One may also note that since the pseudogap in cuprates has multiple origins there is no need to recoin the term suggested by Mott.
Casimir effect between superconductors
A recent experiment [Norte et al. Phys. Rev. Lett. 121, 030405 (2018)] probed the variation of the Casimir force between two closely spaced thin Al films as they transition into a superconducting state, observing a null result. We present here computations of the Casimir effect for superconductors, based on the Mattis-Bardeen formula for their optical response. We show that for the Al system used in the experiment the effect of the transition is over 250 times smaller than the experimental sensitivity, in agreement with the observed null result. We demonstrate that a large enhancement of the effect can be achieved by using a system consisting of a Au mirror and a superconducting NbTiN film. We estimate that the effect of the superconducting transition would be observable with the proposed Au-NbTiN configuration, if the sensitivity of the apparatus could be increased by an order of magnitude.