Symmetry Analysis of Magnetoelectric Effects in Perovskite-Based Multiferroics

In this article, we performed symmetry analysis of perovskite-based multiferroics: bismuth ferrite (BiFeO3)-like, orthochromites (RCrO3), and Ruddlesden–Popper perovskites (Ca3Mn2O7-like), being the typical representatives of multiferroics of the trigonal, orthorhombic, and tetragonal crystal families, and we explored the effect of crystallographic distortions on magnetoelectric properties. We determined the principal order parameters for each of the considered structures and obtained their invariant combinations consistent with the particular symmetry. This approach allowed us to analyze the features of the magnetoelectric effect observed during structural phase transitions in BixR1−xFeO3 compounds and to show that the rare-earth sublattice has an impact on the linear magnetoelectric effect allowed by the symmetry of the new structure. It was shown that the magnetoelectric properties of orthochromites are attributed to the couplings between the magnetic and electric dipole moments arising near Cr3+ ions due to distortions linked with rotations and deformations of the CrO6 octahedra. For the first time, such a symmetry consideration was implemented in the analysis of the Ruddlesden–Popper structures, which demonstrates the possibility of realizing the magnetoelectric effect in the Ruddlesden–Popper phases containing magnetically active cations, and allows the estimation of the conditions required for its optimization.

Demonstration of Dipole-Induced Transparency Using Mirrored Split-Ring Resonator Metasurface For Microwave Applications

In this paper, dipole-induced transparency in the microwave regime is proposed and verified using experimental and simulation studies. A single layer mirrored Split-Ring Resonator (SRR) metasurface array working under the H⊥excitation scenario is used to achieveout-of-phase electric dipole moments on the metasurface for a normal incident plane wave. The emergence of the transparency window is accompanied by the destructive interference between out-of-phase oscillating electric dipole moments on the metasurfaceand is verified in computations by studying the radar Cross Section in full-wave electromagnetic simulations.We used the multipole scattering theory to validate the results computationally. The coupling effects are studied numerically, and the emergence of the transparency window is studied experimentally using transmission measurements inside an anechoic chamber using a vector network analyzer.

Dipole Moment and Pressure Dependent Interlayer Excitons in MoSSe/WSSe Heterostructures

The broken mirror symmetry of the two-dimensional (2D) Janus material brings novel quantum properties and various application prospects. Particularly, when stacking into heterostructure, its intrinsic dipole moments and large band...

Application of LFER to pKas and Dipole Moments of 1H and 2H Tautomers of Tetrazole: Mimicking Structure-Function Relation as a Chemical Education Perspective

Structure-function relation is a 155 year old concept to explain the dependence of biological activity of a drug molecule on its structure put forward by Crum-Brown and Fraser*. Similar line of interest is followed in the present work, and it stimulates the understanding of structure-activity relation (SAR) among the graduate students. An attempt is made for the first time from our laboratory to apply the Hammett and Taft equations to a five membered ring system with four nitrogens as heteroatoms viz. tetrazole to identify the aqueous medium 1H and 2H Tautomers. For this purpose experimentally determined aqueous medium pKa values of NH-acidities of a total of fifteen 5-X-1,2,3,4-tetrazoles and DFT/B3LYP method at the 6-31G* level calculated dipole moments of seven 1H and 2H tautomers of 5-X-1,2,3,4-tetrazoles are used to correlate with Hammett para and meta, and Taft _ortho^* values. Good correlations are obtained. The promising response of more abundant and more polar 1H tautomer with less susceptibility (* = -1.38 in pKa correlations and * = -0.55 in dipole moments correlation) to Taft equation and less abundant and less polar 2H tautomer with more susceptibility (para = 6.56, meta = 7.79 in pKa correlations, and para = 2.69, meta = 3.26 in dipole moments correlation) to Hammett equation of the tetrazole is well distinguished. Thus it mimics a principle of structure-function study on a chemical property like the ionization of NH proton of tetrazole and on a physical property like dipole moment for the first time. Therefore finding a way is achieved to get the equilibrium identification of 1H and 2H tautomers without using any expensive and time consuming experimental techniques.