Designing the collective non-local responses of metasurfaces

The ability to design the electromagnetic properties of materials to achieve any given wave scattering effect is key to many technologies, from communications to cloaking and biological imaging. Currently, common design methods either neglect degrees of freedom or are difficult to interpret. Here, we derive a simple and efficient method for designing wave–shaping materials composed of dipole scatterers, taking into account multiple scattering effects and both magnetic and electric polarizabilities. As an application of our theory, we design aperiodic metasurfaces that re-structure the radiation from a dipole emitter: (i) modifying of the near-field to provide a 4-fold enhancement in power emission; (ii) re-shaping the far-field radiation pattern to exhibit chosen directivity; and (iii) the design of a discrete Luneburg–like lens. Additionally, we develop a clear physical interpretation of the optimised structure, by extracting eigen-polarizabilities of the system, finding that a large eigen-polarizability corresponds to a large collective response of the scatterers.

A 3D-printed molecular ferroelectric metamaterial

Molecular ferroelectrics combine electromechanical coupling and electric polarizabilities, offering immense promise in stimuli-dependent metamaterials. Despite such promise, current physical realizations of mechanical metamaterials remain hindered by the lack of rapid-prototyping ferroelectric metamaterial structures. Here, we present a continuous rapid printing strategy for the volumetric deposition of water-soluble molecular ferroelectric metamaterials with precise spatial control in virtually any three-dimensional (3D) geometry by means of an electric-field–assisted additive manufacturing. We demonstrate a scaffold-supported ferroelectric crystalline lattice that enables self-healing and a reprogrammable stiffness for dynamic tuning of mechanical metamaterials with a long lifetime and sustainability. A molecular ferroelectric architecture with resonant inclusions then exhibits adaptive mitigation of incident vibroacoustic dynamic loads via an electrically tunable subwavelength-frequency band gap. The findings shown here pave the way for the versatile additive manufacturing of molecular ferroelectric metamaterials.

Room temperature magnetoelectric coupling in a molecular ferroelectric ytterbium(III) complex

Magnetoelectric (ME) materials combine magnetic and electric polarizabilities in the same phase, offering a basis for developing high-density data storage and spintronic or low-consumption devices owing to the possibility of triggering one property with the other. Such applications require strong interaction between the constitutive properties, a criterion that is rarely met in classical inorganic ME materials at room temperature. We provide evidence of a strong ME coupling in a paramagnetic ferroelectric lanthanide coordination complex with magnetostrictive phenomenon. The properties of this molecular material suggest that it may be competitive with inorganic magnetoelectrics.

DEUTERON ELECTRIC QUADRUPOLE AND OCTUPOLE POLARIZABILITIES

The direct transition-matrix approach to determination of the electric polarizabilities of quantum bound systems developed in my preceding work is applied to study the electric multipole polarizabilities of a two-particle bound complex with a central interaction between the particles. Expressions for the electric quadrupole and octupole polarizabilities of the deuteron are derived and their values in the case of the S-wave separable interaction potential are calculated.

Density functional theory study on the structural, reactivity, and electronic properties of all mono-, di-, tri-, tetra-, and penta-fluoroanilines as monomers for conducting polymers

Electrical and structural properties of mono-, di-, tri-, tetra-, and penta-fluoroanilines as candidate monomers for new conducting polymers have been investigated using hybrid density functional theory (B3LYP/6–311+G**) based methods. The effects of the number and position of the fluorine atoms on the electrical and structural properties of fluoroanilines and their radical cations have also been investigated. The values of the vibrational frequencies, charge and spin-density distributions, ionization potentials, dipole moments, electric polarizabilities, HOMO-LUMO gaps, and the NICS values of these compounds have been calculated and analyzed as well. The results showed that the double bonds in 2-fluoroaniline and 2,5-difluoroaniline are more delocalized compared with other fluoroanilines; therefore, these molecules have the most aptitude for the electropolymerization reactions. The frequency analysis showed that the electrochemical stability of 2-fluoroaniline is greater than the other fluoroanilines. Also, this molecule possesses the largest NICS value compared to the other fluoroanilines. Consequently, 2-fluoroaniline has the largest ring current and the highest conductivity among all other monomers. Based on the results obtained, 2-fluoroaniline and 2,5-difluoroaniline are the best candidate monomers among all fluoroanilines for the synthesis of corresponding conducting polymers.