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• Owing to the formation of hybridized minibands, twisted homobilayer TMDs provide new and intriguing platforms for investigating not only momentum direct K-K intralayer excitons, but also momentum-indirect Γ–K and Γ–Q interlayer excitons. • We have modulated the momentum-indirect Γ–Q and Γ–K transitions of twisted homobilayer MoSe 2 sample (with the angle near 60°) by external electric fields and observed non-zero linear stark shift for these lower-energy peaks. • Power dependent PL spectra reveals the localized nature of moiré excitons. Twist, the very degree of freedom in van der Waals heterostructures, offers a compelling avenue to manipulate and tailor their electrical and optical characteristics. In particular, moiré patterns in twisted homobilayer transition metal dichalcogenides (TMDs) lead to zone folding and miniband formation in the resulting electronic bands, holding the promise to exhibit inter-layer excitonic optical phenomena. Although some experiments have shown the existence of twist-angle-dependent intra- and inter-layer excitons in twisted MoSe 2 homobilayers, electrical control of the interlayer excitons in MoSe 2 is relatively under-explored. Here, we show the signatures of the moiré effect on intralayer and interlayer excitons in 2H-stacked twisted MoSe 2 homobilayers. Doping- and electric field-dependent photoluminescence measurements at low temperatures give evidence of the momentum-direct K–K intralayer excitons, and the momentum-indirect Γ–K and Γ–Q interlayer excitons. Our results suggest that twisted MoSe 2 homobilayers are an intriguing platform for engineering interlayer exciton states, which may shed light on future atomically thin optoelectronic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Growth-induced surface wrinkling in constrained bilayers comprising a thin film attached to a thick substrate is a canonical model for understanding pattern formation in many biological systems. While the bilayer model has received much prior attention, the nonlinear behaviour for arrangements with similar film and substrate properties, or substrate growth that outpaces film growth, remains poorly understood. This paper therefore focuses on these cases in which the substrate's elasticity dominates surface wrinkling. By combining analytical modelling and finite element simulations incorporating advanced path-following techniques, we characterise critical wrinkling states and explore the initial and advanced post-buckling behaviour for a wide range of film-to-substrate modulus and growth rate ratios. It is shown that the classical leading-order asymptotic expression for the critical strain is not of sufficient accuracy for film-to-substrate modulus ratios below 50, and higher order correction terms are presented. Leveraging a weakly nonlinear analytical model, we introduce a phase diagram categorising stable and unstable post-buckling regimes. Advanced path-following simulations are employed to unveil the evolution of wrinkling patterns, from initial sinusoidal instabilities to complex formations involving period doubling, quadrupling, and eventual surface creasing. These comprehensive phase diagrams, parameterised by film-to-substrate modulus and growth rate ratios, provide new insights into the rich dynamics of surface wrinkling. Finally, we demonstrate the existence of multi-stability in the advanced post-buckling regimes for bilayers experiencing substrate-dominated growth. This work contributes to the understanding of the mechanics underlying pattern formation in growing bilayers over the entire parameter regime, with potential implications for explaining biological morphogenesis and informing the development of novel diagnostic tools and artificial flexible electronic skins. [Display omitted] • The film–substrate stiffness ratio is no more than 50 and substrate grows faster than film. • Asymptotic expressions for the critical growth and wavenumber are derived. • Weakly nonlinear analysis is conducted to determine the nature of the first bifurcation. • Advanced numerical methods are used to categorise behaviour in the fully nonlinear regime. • A finite set of wrinkling patterns are found as building blocks for multiple stable states. [ABSTRACT FROM AUTHOR]

A study conducted by researchers at Nanyang Technological University in Singapore has found that the protonation state of a bioactive compound affects its release from lamellar gel-phase bilayers. The researchers used molecular dynamics simulations to determine that the protonated form of cinnamic acid, an antimicrobial food additive, has a higher retention ratio than its deprotonated counterpart in the bilayer. The study also emphasizes the importance of considering the oligomeric states of molecules when estimating their permeability within bilayers. The research was supported by the Agency for Science Technology & Research (ASTAR) and has been peer-reviewed. [Extracted from the article]

The effects of out-of-plane deformation on atomic relaxation in twisted van der Waals bilayers are investigated by comprehensive multiscale modeling and simulations. The model integrates the DFT-informed generalized stacking-fault energy for interlayer interaction between layers and the Föppl–von Kármán plate theory for elastic energy in each layer with minimization of the total free energy for atomic relaxation governed by a gradient flow method. Our simulation results elucidate twist-angle dependent moiré pattern, strain field, tortional displacement field and stacking domain structures, in good agreement with recent experimental observations. In particular, we derive the strain soliton solution at a small twist angle and the soliton free elastic solution at a large twist angle for the reconstructed van der Waals bilayer with out-of-plane deformation. These results show that out-of-plane deformation not only modifies the strain soliton width but also induces substantial alterations in the strain field, local rotation, and stacking structures. Our findings reveal the non-neglectable role played by out-of-plane deformation in the atomic relaxation of twisted van der Waals bilayers, particularly at smaller twist angles. The intricate interplay between in-plane atomic relaxation and out-of-plane deformation provides opportunities for strain engineering in twisted van der Waals bilayers. [ABSTRACT FROM AUTHOR]

Researchers at Nanjing University have reported new data on physics related to the control of biomolecular clusters and condensates on cell membranes. They propose a method to control receptor condensation on the cell membrane through adhesion to a supported lipid bilayer (SLB) with nanoscale topography. The nanoscale topography of the SLB enhances the condensation of receptors associated with lipid nanodomains. This research suggests that SLBs with nanoscale topography can be used to control and direct cellular activities, such as stem cell differentiation, for biomedical and therapeutic applications. [Extracted from the article]

A new report from the University of Science and Technology Beijing presents fresh data on applied physics. The research focuses on the observation of robust chiral spin torques and non-reciprocal charge transport behaviors in a-Fe2O3/Pt bilayers. The study establishes the important role of interfacial magnetic chirality in determining charge and spin transport behaviors in antiferromagnetic insulator/heavy metal bilayer systems. The findings contribute to the broader understanding of spintronics and related fields, and have implications for the advancement of these areas. [Extracted from the article]

A recent study conducted by researchers at California State University Sacramento explores the question of how proton concentration gradients across cellular membranes developed in ancestral protocells. The researchers used liposomes as models of primitive cells and were able to generate proton gradients using redox reactions as the driving force. They propose that sulfite, which would have been abundant in early cells, may have been a primary source of redox energy for primitive chemiosmotic energy transduction. This research provides insight into the origin of life and the evolution of complex forms of life on Earth. [Extracted from the article]

Abstract This work presents a general methodology to analyze three-dimensional Freedericksz transitions in twisted-nematic liquid crystal (LC) bilayers. Using two equivalent coupled electromechanical variational formulations, the problem is treated as a bifurcation instability triggered by an externally applied electric field. Specifically, we consider LC bilayer materials anchored between two bounding plates and subjected to an electric field across the bilayer thickness. The plates are also twisted by an overall angle leading to different orientations of the directors in each layer. We first evaluate the corresponding ground state of the director field, and subsequently, we analyze the bifurcation problem by using a combined analytical-numerical method leading to a one-dimensional finite element discretization of the resulting stiffness matrix of the system. An analytical solution for the zero-twist bilayer is also obtained. The developed methodology is used to study the effect of the volume fraction of the constituents forming the bilayer upon the resulting critical electric field and corresponding eigenmodes. We find that by assembling a relatively thin 5CB layer with a thicker 7E layer, one can obtain periodic Freedericksz transitions (i.e. local modes) even for a zero-twist LC bilayer. We also show that when a 5CB material is assembled together with another electrically similar LC, such as a PCH12, the combined LC bilayer can exhibit an even lower Freedericksz transition than a LC of the same thickness consisting of any of the two constituents alone. [ABSTRACT FROM AUTHOR]

We propose a model to realize a fermionic superfluid state in an optical lattice circumventing the cooling problem. Our proposal exploits the idea of tuning the interaction in a characteristically low-entropy state, a band insulator in an optical bilayer system, to obtain a superfluid. By performing a detailed analysis of the model including fluctuations and augmented by a variational quantum Monte Carlo calculation of the ground state, we show that the superfluid state obtained has a high transition temperature of the order of the hopping energy. Our system is designed to suppress other competing orders such as a charge density wave. We suggest a laboratory realization of this model via an orthogonally shaken optical lattice bilayer. [ABSTRACT FROM AUTHOR]

We investigate a dilute Fermi gas of polar molecules confined into a bilayer setup with dipole moments polarized perpendicular to the layers. In particular, we consider the extreme case of population imbalance, where we have only one particle in one layer and many particles in the other one. The single molecule is attracted by the dilute Fermi gas through the interlayer dipole-dipole force, presenting an interesting impurity problem with long-range anisotropic interaction. We characterize the quasiparticle, calculating its chemical potential with a Brueckner-Hartree-Fock approach. Moreover, we determine the momentum relaxation rate for finite momentum and temperature. The latter is reminiscent of Coulomb drag in bilayer electronic systems. For a confined system we relate the results for the chemical potential with the measurement of the oscillation frequency of the impurity. The momentum relaxation rate provides instead an estimate on how quickly the oscillations are damped. [ABSTRACT FROM AUTHOR]

The article focuses on a research conducted by the Berkeley Lab researchers which stated that graphene bilayers can bring certain changes in the electronic properties of graphene.