Article
Physics, Multidisciplinary
M. Liu, Y. Zhang, G. L. Klimchitskaya, V. M. Mostepanenko, U. Mohideen
Summary: The experimental confirmation of the unusually big thermal effect at separations below 1 μm for graphene suggests that its effective temperature is determined by the Fermi velocity rather than the speed of light.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Natalia Emelianova, Nail Khusnutdinov, Rashid Kashapov
Summary: In this study, explicit formulas for the Casimir energy of parallel sheets composed of conducting planes with tensorial conductivities were derived using the scattering matrix approach. Formulas for the Casimir energy and force acting on the planes within a stack of graphene were obtained by solving the recurrence relations. The binding energy in the graphene stack with graphite interplane separation was also calculated and found to be E-ib = 9.9 meV/atom. Notably, the Casimir force on graphene sheets decreases rapidly for planes beyond the first one, with the force on the second graphene layer being 35 times smaller than that experienced by the first layer.
Article
Physics, Nuclear
G. L. Klimchitskaya, U. Mohideen, V. M. Mostepanenko
Summary: This article reviews the Casimir effect in graphene systems, with a focus on the large thermal correction to the Casimir force predicted at short separations between test bodies. Computational results are presented for the Casimir pressure and thermal correction in both pristine graphene and real graphene sheets, obtained using the exact polarization tensor. Two experiments are described, which measure the gradient of the Casimir force between an Au-coated sphere and graphene-coated substrates using a modified atomic force microscope cantilever-based technique. The measurement data from both experiments are shown to be in agreement with theoretical predictions, and the second experiment demonstrates the predicted large thermal effect at short separations. The potential implications of this result for resolving long-standing problems in Casimir physics are discussed.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2022)
Article
Chemistry, Physical
Ivan Santamaria-Holek, Agustin Perez-Madrid
Summary: Using an innovative approach based on Planck's law, this study explores the common origin of the repulsive Casimir thermal pressure and heat exchange in nanogaps. By employing a scale transformation, the researchers demonstrate the validity of Planck's law in describing confined thermal radiation properties in nanoscale gaps. Analytical expressions for the Casimir thermal pressure and heat conductance are derived and compared with experimental data, showing remarkable agreement.
NANOSCALE HORIZONS
(2022)
Article
Multidisciplinary Sciences
Galina L. Klimchitskaya, Constantine C. Korikov, Vladimir M. Mostepanenko, Oleg Yu. Tsybin
Summary: This study investigates the out-of-thermal-equilibrium Casimir-Polder force between nanoparticles and dielectric substrates coated with gapped graphene using the Dirac model and the polarization tensor formalism. The results show that the presence of a substrate can increase the magnitude of the nonequilibrium force. The temperature of the graphene-coated substrate also affects the force magnitude.
Article
Physics, Particles & Fields
G. Alencar, V. B. Bezerra, C. R. Muniz
Summary: This paper investigates that in (2+1) dimensions, wormholes cannot be sourced solely by both Casimir energy density and tension, unlike in the 4-D scenario where it has been shown that it is possible. The study shows that in 3-D spacetime, the arising of at least an event horizon is inevitable. Introducing a cosmological constant and applying a perpendicular weak magnetic field can circumvent this restriction and contribute to the formation of the wormhole.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Materials Science, Multidisciplinary
M. Liu, Y. Zhang, G. L. Klimchitskaya, V. M. Mostepanenko, U. Mohideen
Summary: The experimental results show that the polarization tensor of graphene can well describe the Casimir force gradient between an Au-coated hollow glass microsphere and a graphene-coated fused silica plate, while also excluding the theoretical predictions at zero temperature. The study also found a correlation between the thermal correction to the Casimir force gradient and factors such as substrate, energy gap, and chemical potential.
Article
Optics
Danilo T. Alves, Lucas Queiroz, Edson C. M. Nogueira, N. M. R. Peres
Summary: This paper investigates the lateral van der Waals (vdW) force between a neutral polarizable point particle and a perfectly conducting infinite cylinder. It is found that under certain conditions, including particle orientation, anisotropy, and cylinder curvature, the lateral vdW force can exhibit a repulsive behavior, pushing the particle away from the cylinder. This study extends the understanding of the sign inversion in lateral forces and the characteristics of lateral vdW forces.
Article
Materials Science, Multidisciplinary
S. Pashalou, H. Goudarzi, M. Khezerlou, S. A. Jafari
Summary: The study reveals that the interaction between optical pulse and Higgs mode oscillations in superconductors affects electron dynamics, leading to irreversible transitions between valence and conduction bands in graphene. The presence of superconductivity significantly influences the redistribution of conduction band electrons and hot spots in the Dirac points of graphene, with the number of hot spots depending on pulse intensity.
Article
Astronomy & Astrophysics
Herondy F. S. Mota, Celio R. Muniz, Valdir B. Bezerra
Summary: This paper investigates the thermal fluctuation corrections to the vacuum energy at zero temperature of a conformally coupled massless scalar field in the Einstein universe with a spherical boundary. The results generalize those found in previous literature and calculate the renormalized Casimir free energy, internal energy, and entropy, considering both high and low temperature limits. The study reveals classical contributions along with logarithmic terms at high temperatures, while at low temperatures, the vacuum energy dominates and the entropy obeys the third law of thermodynamics.
Article
Materials Science, Multidisciplinary
Zhen Liu, Bo Wang, Shicheng Wei, Wei Huang, Yujiang Wang, Yi Liang
Summary: Three different graphene foam (GF) were synthesized using ethylene glycol (EG), sodium hypophosphite, and l-ascorbic acid (L-AA) as reductants via a simple hydrothermal method. The choice of reductants significantly affected the micro morphology and microwave absorption (MA) performance of GF, with EG displaying the best MA efficiency. At a filling amount of 2 wt% and a matching thickness of 3.38 mm, the GF with EG as the reducing agent achieved a minimum reflection loss (RLmin) of -55.89 dB, accompanied by an effective absorption bandwidth (EAB) of 6.88 GHz.
Article
Engineering, Electrical & Electronic
Xiaoyuan Lu
Summary: Studying narrowband plasmonic absorbers is critical for achieving higher sensor sensitivity; graphene-based metasurfaces show a narrowband reflection spectrum with high absorption in the infrared range; this structure has potential for biosensing applications, such as monitoring neural stem cell activities during cell development.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Environmental Sciences
Kaiheng Zhu, Qi Liu, Xinyan Xie, Qi Jiang, Yanan Feng, Pei Xiao, Xiaoqian Wu, Ranran Song
Summary: This study found an association between the BDNF gene rs6265 polymorphism and the risk of dyslexia, and that copper exposure could interact with rs6265 to increase the risk of dyslexia.
ENVIRONMENTAL POLLUTION
(2022)
Article
Physics, Multidisciplinary
Kouki Nakata, Kei Suzuki
Summary: Quantum fluctuations, key concepts of quantum mechanics, induce a zero-point energy shift known as the Casimir effect. This phenomenon has attracted attention in various fields, from elementary particle physics to condensed matter physics and photonics. While yttrium iron garnet (YIG) has been extensively studied for spintronics, the application of the Casimir effect to ferrimagnetic thin films has not been explored enough. In this study, using lattice field theory, we investigate the Casimir effect on magnons in insulating magnets and find that it can arise in ferrimagnetic YIG thin films. Our results suggest that YIG can serve as a promising platform for Casimir engineering in magnon-based spintronics.
PHYSICAL REVIEW LETTERS
(2023)
Article
Computer Science, Information Systems
Rizwan A. Farade, Noor Izzri Abdul Wahab, Diaa-Eldin A. Mansour, Norhafiz B. Azis, Jasronita B. T. Jasni, Veerapandiyan Veerasamy, Mariammal Thirumeni, Andrew Xavier Raj Irudayaraj, Avinash Srikanta Murthy
Summary: The study focuses on developing nonedible green nanofluids based on cottonseed oil, using additive graphene nanoparticles and surfactant to investigate and compare their dielectric and thermal properties, as well as exploring their long-term stability.
Review
Astronomy & Astrophysics
Vladimir M. Mostepanenko
Summary: This paper reviews the complicated problems in Lifshitz theory describing the Casimir force between real material plates made of metals and dielectrics. Experimental data exclude the theoretical Casimir forces calculated within the framework of Lifshitz theory, leading to the proposal of various approaches to resolve this issue.
Editorial Material
Astronomy & Astrophysics
Nazar R. Ikhsanov, Galina L. Klimchitskaya, Vladimir M. Mostepanenko
Article
Multidisciplinary Sciences
Galina L. Klimchitskaya, Vladimir M. Mostepanenko, Oleg Yu Tsybin
Summary: The study focused on the Casimir pressure in peptide films deposited on different dielectric or metallic substrates. It was found that for dielectric-type semiconductor substrates, the thickness of the film determines whether the Casimir pressure is attractive or repulsive, depending on the percentage of water and the static dielectric permittivity of the semiconductor substrate; while for metallic-type semiconductor substrates, the Casimir pressure in peptide coatings is always repulsive.
Review
Multidisciplinary Sciences
Michael Bordag
Summary: This article reviews the instabilities that arise from the coupling of spin-one fields to a magnetic background in a non-Abelian theory. The coupling contributes to the effective potential due to asymptotic freedom in a negative quantum. The Savvidy vacuum emerges in QCD, but its instability caused by the tachyonic mode leaves the true ground state of QCD still open. In the electroweak model, the corresponding instability is postponed to very large background fields and may be relevant in the early universe.
Article
Physics, Nuclear
M. Bordag
Summary: In this paper, the issue of chromomagnetic vacuum in SU(2) is studied, revealing a minimum below zero in the effective Lagrangian in the one-loop approximation, leading to the spontaneous generation of a magnetic field. However, this minimum is unstable due to the presence of an imaginary part in the effective action. Numerous attempts have been made to address this issue, all of which have been unsatisfactory to some extent. A new solution is proposed by considering the condensate formation of the tachyonic mode at low temperature, resulting in a phase transition similar to the Higgs model. The approximation with only the tachyonic mode and an O(2)-model with quartic self-interaction in two dimensions is considered. The CJT (2PI) formalism in Hartree approximation is applied, revealing a minimum of the effective action at a certain value of the condensate and background fields at zero and low temperatures, with no imaginary part. As the temperature increases, this minimum becomes shallower, and at a critical temperature, the perturbative state with lower effective potential becomes dominant, restoring the symmetry. The physically interpreted mechanism states that the unstable mode creates tachyons until they reach equilibrium through repulsive self-interactions and form a condensate. The relation to the Mermin-Wagner theorem is discussed.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Review
Physics, Multidisciplinary
Galina L. Klimchitskaya, Vladimir M. Mostepanenko
Summary: This article reviews the scientific pictures of the universe from ancient times to Albert Einstein and highlights Alexander Friedmann's prediction of the universe expansion. It discusses the experimental confirmation of this prediction and the implications it has on our understanding of the world.
Article
Materials Science, Multidisciplinary
G. L. Klimchitskaya, V. M. Mostepanenko, O. Yu. Tsybin
Summary: In this study, the nonequilibrium Casimir-Polder force between a nanoparticle and a graphene sheet kept at different temperatures was examined using the formalism of the polarization tensor in the framework of a Dirac model. The results demonstrate that the magnitude of the force increases with the temperature of the graphene sheet. The impact of nonequilibrium conditions on the force becomes smaller at larger separations. Our findings reveal that for a graphene sheet with a lower temperature than the environment, the attractive Casimir-Polder force vanishes at a specific separation distance and becomes repulsive at larger distances. This effect has potential applications in fundamental graphene research and force control in bioelectronic microdevices.
Article
Physics, Particles & Fields
M. Bordag, V Skalozub
Summary: This paper investigates the behavior of the effective action or free energy in SU(2) gluodynamics at finite temperature, when both A(0) background and magnetic background are present. The results show that the imaginary part is still present at the two-loop level, and the real part exhibits an unnatural singularity in the region where the imaginary part sets in.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Optics
G. L. Klimchitskaya, V. M. Mostepanenko
Summary: The paper introduces a new phenomenological dielectric function for metals, which exhibits similar response as the standard Drude model for propagating waves but different response for evanescent waves. Using this function, the effective Casimir pressure and force between different test bodies are calculated and compared with measurement data. The results show that the predictions of the Lifshitz theory using the dissipative nonlocal response functions are in good agreement with the measurement data.
Article
Astronomy & Astrophysics
G. L. Klimchitskaya, V. M. Mostepanenko
Summary: The Lifshitz theory of the Casimir force was extended to parallel magnetic metal plates with nonlocal dielectric responses. Results showed minimal differences in Casimir pressures between different nonlocal and local response functions at short separations but significant discrepancies at a few micrometer distances. The gradient of the Casimir force between Ni-coated surfaces of a sphere and a plate using alternative nonlocal response functions demonstrated good agreement with measurement data, providing insights for resolving longstanding problems in Casimir physics.