Giant magnon spin conductivity approaching the two-dimensional transport regime in ultrathin yttrium iron garnet films

Conductivities are key material parameters that govern various types of transport (electronic charge, spin, heat etc.) driven by thermodynamic forces. Magnons, the elementary excitations of the magnetic order, flow under the gradient of a magnon chemical potential in proportion to a magnon (spin) conductivity σm. The magnetic insulator yttrium iron garnet (YIG) is the material of choice for efficient magnon spin transport. Here we report an unexpected giant σm in record-thin YIG films with thicknesses down to 3.7 nm when the number of occupied two-dimensional (2D) subbands is reduced from a large number to a few, which corresponds to a transition from 3D to 2D magnon transport. We extract a 2D spin conductivity (≈1 S) at room temperature, comparable to the (electronic) spin conductivity of the high-mobility two-dimensional electron gas in GaAs quantum wells at millikelvin temperatures. Such high conductivities offer unique opportunities to develop low-dissipation magnon-based spintronic devices.

De novo synthesis of hybrid d-f block metal complex salts for electronic charge transport applications

The advent of the d-d type of complex salts in designing smart functional materials of versatile utility inspired us to develop a novel type of M(II)-Ce(IV) complex salts [M(II) =...

Tuning Charge Order in (TMTTF)2X by Partial Anion Substitution

In the quasi-one-dimensional (TMTTF)2X compounds with effectively quarter-filled bands, electronic charge order is stabilized from the delicate interplay of Coulomb repulsion and electronic bandwidth. The correlation strength is commonly tuned by physical pressure or chemical substitution with stoichiometric ratios of anions and cations. Here, we investigate the charge-ordered state through partial substitution of the anions in (TMTTF)2[AsF6]1−x[SbF6]x with x≈0.3, determined from the intensity of infrared vibrations, which is sufficient to suppress the spin-Peierls state. Our dc transport experiments reveal a transition temperature TCO = 120 K and charge gap ΔCO=430 K between the values of the two parent compounds (TMTTF)2AsF6 and (TMTTF)2SbF6. Upon plotting the two parameters for different (TMTTF)2X, we find a universal relationship between TCO and ΔCO yielding that the energy gap vanishes for transition temperatures TCO≤60 K. While these quantities indicate that the macroscopic correlation strength is continuously tuned, our vibrational spectroscopy results probing the local charge disproportionation suggest that 2δ is modulated on a microscopic level.

The Chirality of Isotopomers of Glycine Compared using Next-Generation QTAIM

The effect of the presence of a deuterium (D) or tritium (T) isotope bonded to the alpha carbon of glycine is determined without the need to apply external forces e.g. electric fields or using normal mode analysis. Isotopic effects were accounted for using the mass-dependent diagonal Born-Oppenheimer energy correction (DBOC) at the CCSD level of theory. We calculated the stress tensor trajectories of the dominant C-N bond within next generation quantum theory of atoms in molecules (NG-QTAIM). S-character chirality was discovered using the stress tensor trajectories, instead of the Cahn–Ingold–Prelog (CIP) rules, for ordinary glycine. The S-character chirality was preserved after the substitution of the H on the alpha carbon for a D isotope but transformed to R-character chirality after replacement with the T isotope. This reversal of the chirality depending on the presence of a single D or T isotope bound to the alpha carbon adds to the debate on the nature of the extraterrestrial origins of chirality in simple amino acids. We demonstrate that NG-QTAIM is a promising tool for understanding isotopic induced electronic charge density changes, useful in analysis of infrared (IR) or circular dichroism (CD) spectra explaining changes in mode couplings and bands intensities or sign.

Computational studies on Emodin (C15H10O5) from Methanol extract of Pteridium acquilinum leaves

This research isolates, characterizes, and studies the computational and frequency calculations of emodin, extracted from the leaf extract of Pteridium acquilinum leaves using methanol. Vacuum liquid and tin layer Chromatography was used for the purification of the molecule. The (VLC purified), fraction was analyzed by Nuclear magnetic resonance (NMR) and the chemical structure of the compound isolated (anthraquinone), was confirmed by 1H & 13C-NMR analyses as emodin (C15H10O5). Computational and frequency studies have been done on the isolated molecule. Optimized geometry, IR frequencies, Bond distances (R) and angles (A), Dipole moments and other parameters have been computationally determined for the isolated molecule from quantum chemical calculations using the GAUSSIAN 09 retinue programs. Experimentally determined and computationally measured IR frequencies agree perfectly with each other. Computational studies can be used to predict unobserved chemical phenomena like design of new drugs and materials such as the positions of constituent atoms in relationship to their relative and absolute energies, electronic charge densities, dipoles, higher multiple moments, vibrational frequencies, relativity or other spectroscopic quantities and cross sections for collision with other molecules. This is the first time this anthraquinone, [emodin], with most of the parameters examined is reported from P. aquilinum.

Role of MXenes/Polyaniline Nanocomposites in Fabricating Innovative Supercapacitor Technology

Versatile and exclusive electronic, optical, physicochemical, electrochemical and mechanical features of both conducting polymers and MXenes have stimulated global scientists to take serious impetuses in designing innovative high-performance energy storage systems with these materials, for resolving the growing needs for auto-powering mechanically flexible and wearable electronics for all essential technological fields. However, both the materials have experienced some serious practical limitations, which have driven the scientific community to look for necessary modifications in the form of MXenes/PANI nanocomposites with suitable compositions that would essentially restore their representative characteristics but successfully suppress their functional drawbacks concurrently and considerably. Accordingly, in the present overview, the different strategies of fabrication of MXenes/PANI nanocomposites for advanced supercapacitors with special reference to the necessary morphological modifications brought about by synthetic improvisations that resulted in superior capacitive, electronic charge transport as well as structural properties have also been recognized and compared. Such analysis would purposefully assist in adjusting the integral mechanical and electrochemical responses for scheming smarter and highly flexible microelectronics soon.

Using plasmons to harness infrared solar light

Using plasmons to harness infrared solar light The PLASMIONICO project aims to advance the sustainable production of electricity by harnessing infrared (IR) solar light, which is typically wasted in conventional solar cells. The key concept is to allow IR light to be absorbed at nanostructured metal cathodes to launch surface plasmons (rapid oscillations of electronic charge analogous to sound waves in liquids) to generate a photocurrent. Our strategy uses inverted silicon pyramid arrays covered with thin gold films, manufactured employing low-cost and scalable methods. After optimising the infrared absorption performance, we are set to improve photocurrent delivery with promising results.