A further comparison of graphene and thin metal layers for plasmonics

Which one is much more suitable for plasmonic materials, graphene or metal? To address this problem well, the plasmonic properties of thin metal sheets at different thicknesses have been investigated and compared with a graphene layer. As demonstration examples, the propagation properties of insulatormetal-insulator and metamaterials (MMs) structures are also shown. The results manifest that the plasmonic properties of the graphene layer are comparable to that of thin metal sheets with the thickness of tens of nanometers. For the graphene MMs structure, by using the periodic stack structure in the active region, the resonant transmission strength significantly improves. At the optimum period number, 3-5 periods of graphene/SiO2, the graphene MMs structure manifests good frequency and amplitude tunable properties simultaneously, and the resonant strength is also strong with large values of the Q-factor. Therefore, graphene is a good tunable plasmonic material. The results are very helpful to develop novel graphene plasmonic devices, such as modulators, antenna and filters

Tunable graphene opto-electronics devices

Higgs is the only scalar particle that already observed up to now.In the standard model of particle physics,Higgs plays a very important role.On the other hand,inflation is also driven by scalar field called inflaton.Higgs boson can not be the inflaton since the large hierarchy energy scale of the mass between inflaton and itself.However,by using some indirectly method,inflaton could be another aspect of the Higgs boson.In this paper,the authors review some Higgs inflation models and discuss the role of the cosmological constant during inflation

Band structure and dispersion engineering of strongly coupled plasmon-phonon-polaritons in graphene-integrated structures

Publisher's PDFWe theoretically investigate the polaritonic band structure and dispersion properties of graphene using transfer matrix methods, with strongly coupled graphene plasmons (GPs) and molecular infrared vibrations as a representative example. Two common geometrical con- figurations are considered: graphene coupled subwavelength dielectric grating (GSWDG) and graphene nanoribbons (GNR). By exploiting the dispersion and the band structure, we show the possibility of tailoring desired polaritonic behavior in each of the two configurations. We compare the strength of coupling occurring in both structures and find that the interaction is stronger in GNR than that of GSWDG structure as a result of the stronger field confinement of the edge modes. The band structure and dispersion analysis not only sheds light on the physics of the hybridized polariton formation but also offers insight into tailoring the optical response of graphene light-matter interactions for numerous applications, such as biomolecular sensing and detection.University of Delaware. Bartol Research Institute

Fatigue properties and intrinsic mechanism for the environmental-friendly piezoelectric materials for actuator applications

We calculate the tensor-to-scalar ratio in a G-inflation in this paper.In our model,we can avoid the behavior that the contribution of higher order is too much to screen the lower order Lagrangian,or vice versa.Every order Lagrangian of Galileons contribute to the result.Choosing a proper parameter,the tensor-to-scalar ratio of our model is little smaller than the ratio of one field Slow-roll inflation.However,this result can fit much better with BICEP

The electrocaloric effect of Bi_0.5Na_0.5TiO₃-based solid solution withthe composition around the morphotropic phase boundary

Recently,the electrocaloric effect of ferroelectric materials has attracted much attention at home and abroad due to its potential applications in solid-state refrigeration.In this paper,based on Maxwell relations,we study the electrocaloric effect of Bi0.5Na0.5TiO3-based lead-free ferroelectric quasi-solid solution with the composition focusing around the morphotropic phase boundary.The results show that the system has excellent refrigeration characteristics under external electric field of 5 kV/mm and the amount of change in temperature reaches 1.15 K.The corresponding refrigeration strength reaches 0.23 K·mm/kV,showing the prospect of applications in new environmental-friendly solid-state cooling devices

Pyroelectric properties of Mn-doped Aurivillius ceramics with different pseudo-perovskite layers

The pyroelectric properties of Mn-doped Aurivillius ceramics with different pseudo-perovskite layers were investigated. The pyroelectric coefficients for 0.2 wt% Mn-doped two-layer CaBi 2 Nb 2 O 9 (CBN-Mn), three-layer Bi 4 Ti 2.85 Nb 0.15 O 12 (BTN-Mn), and four-layer CaBi 4 Ti 3.95 Nb 0.05 O 15 (CBTN-Mn) ferroelectric ceramics were found to be on the order of 26.0, 54.4, 84.4 μC/m 2 K at room temperature, respectively. These values were closely associated with the number of octahedral layers in the pseudo-perovskite blocks. The high pyroelectric coefficient, together with low dielectric permittivity and loss (tan δ \u3c 0.003), results in to high figures of merit for the current responsivity, voltage responsivity, and detectivity. The excellent pyroelectric properties and high Curie temperatures (T C \u3e 660°C) make the Aurivillius ceramics potential candidates for pyroelectric devices over a broad temperature range

Enhanced pyroelectric and piezoelectric responses in W/Mn-codoped Bi4Ti3O12Aurivillius ceramics

The pyroelectric and piezoelectric properties of 4 at% Mn-doped Bi4Ti2.9W0.1O12(BiTW-Mn) Aurivillius ceramic were investigated and compared to Bi4Ti2.9W0.1O12(BiTW) counterpart, which were fabricated using a conventional solid state reaction method. High resistivities of 4.9 x 1012and 2.5 x 1011Ω cm at 100 °C were obtained in the W-doped and W/Mn-codoped BiT ceramics, respectively. They showed similar activation energies and ionic-p-type mixed conduction mechanisms. Higher pyroelectric coefficients of 57.1 μC/m2K and piezoelectric coefficients of 21 pC/N, as well as much lower dielectric loss of 0.003 were achieved in W/Mn-codoped ceramics. These property changes were mainly induced by MnTi−Vodefect dipoles. The effect of acceptor doping was evidenced by an internal bias field, shown by a horizontal offset in the polarization-field behavior. The improved properties together with high thermal stability indicate that BiTW-Mn may be a promising candidate for pyroelectric and piezoelectric devices at elevated temperatures