Uncovering the Lowest Thickness Limit for Room-Temperature Ferromagnetism of Cr1.6Te2.

Metallic ferromagnetic transition metal dichalcogenides have emerged as important building blocks for scalable magnetic and memory applications. Downscaling such systems to the ultrathin limit is critical to integrate them into technology. Here, we achieved layer-by-layer control over the transition metal dichalcogenide Cr1.6Te2 by using pulsed laser deposition, and we uncovered the minimum critical thickness above which room-temperature magnetic order is maintained. The electronic and magnetic structures are explored experimentally and theoretically, and it is shown that the films exhibit strong in-plane magnetic anisotropy as a consequence of large spin-orbit effects. Our study elucidates both magnetic and electronic properties of Cr1.6Te2 and corroborates the importance of intercalation to tune the magnetic properties of nanoscale materials' architectures.

Signatures of a surface spin-orbital chiral metal.

The relation between crystal symmetries, electron correlations and electronic structure steers the formation of a large array of unconventional phases of matter, including magneto-electric loop currents and chiral magnetism1-6. The detection of such hidden orders is an important goal in condensed-matter physics. However, until now, non-standard forms of magnetism with chiral electronic ordering have been difficult to detect experimentally7. Here we develop a theory for symmetry-broken chiral ground states and propose a methodology based on circularly polarized, spin-selective, angular-resolved photoelectron spectroscopy to study them. We use the archetypal quantum material Sr2RuO4 and reveal spectroscopic signatures that, despite being subtle, can be reconciled with the formation of spin-orbital chiral currents at the surface of the material8-10. As we shed light on these chiral regimes, our findings pave the way for a deeper understanding of ordering phenomena and unconventional magnetism.

Sustainable Synthesis of Indole-Substituted Densely Functionalized Pyrrole.

A novel chromatography- and catalyst-free methodology has been developed for the synthesis of poly substituted pyrrole in good yields via a multicomponent reaction of arylglyoxal, 1,3-dicarbonyl, indole, and aromatic amine. This strategy provides various advantages such as simple experimental and workup procedures, mild reaction conditions, no added catalyst, use of green solvent, and simple purification procedure of pure product without using column chromatography. This green method offers a simple and highly effective strategy to synthesize a wide range of indole-pyrrole conjugates in a one-pot operation.

Light-Controlled Magnetoelastic Effects in Ni/BaTiO3 Heterostructures.

Magnetoelastic and magnetoelectric coupling in the artificial multiferroic heterostructures facilitate valuable features for device applications such as magnetic field sensors and electric-write magnetic-read memory devices. In ferromagnetic/ferroelectric heterostructures, the intertwined physical properties can be manipulated by an external perturbation, such as an electric field, temperature, or a magnetic field. Here, we demonstrate the remote-controlled tunability of these effects under visible, coherent, and polarized light. The combined surface and bulk magnetic study of domain-correlated Ni/BaTiO3 heterostructures reveals that the system shows strong sensitivity to the light illumination via the combined effect of piezoelectricity, ferroelectric polarization, spin imbalance, magnetostriction, and magnetoelectric coupling. A well-defined ferroelastic domain structure is fully transferred from a ferroelectric substrate to the magnetostrictive layer via interface strain transfer. The visible light illumination is used to manipulate the original ferromagnetic microstructure by the light-induced domain wall motion in ferroelectric substrates and consequently the domain wall motion in the ferromagnetic layer. Our findings mimic the attractive remote-controlled ferroelectric random-access memory write and magnetic random-access memory read application scenarios, hence facilitating a perspective for room temperature spintronic device applications.

Mixed Mott-Hubbard and charge transfer nature of 4H-SrMnO3thin film on Si (100).

Room temperature electronic structure of polycrystalline 4H-SrMnO3thin film grown on Si (100) substrate has been studied using resonance photo emission spectroscopy and soft x-ray absorption spectroscopy measurements. Presence of charge transfer screen Mn 3dnLfinal state along with the 3dn-1final state at the valence band edge of 4H-SrMnO3thin film confirms that the ground state is strongly mixed between Mn 3dand O 2pstates. The estimated equivalent values of on-site Coulomb interaction energy (U) and O 2pto Mn 3d- charge transfer energy (Δ) (U≈ Δ ≈ 4.8 eV) from the combination of occupied and unoccupied spectra further confirm the intermediate Mott-Hubbard and charge transfer insulator nature of 4H-SrMnO3film. Despite having similar Mn 4+ valence state in 4H-SrMnO3and cubic SrMnO3, 4H phase is observed to reveal much higher band gap ∼1.5 eV than the cubic phase (0.3 eV), which arises due to different MnO6octahedra environment.

Ethyl Lactate: A Green Solvent for Olefin Metathesis.

Compatibility of selected, commercially available ruthenium olefin metathesis catalysts with ethyl lactate as solvent was evaluated using a range of substrates and conditions. In addition, the preparation of a metathesis catalyst in simplified manner by using the advantages of ethyl lactate was accomplished. The application of ethyl lactate facilitates product isolation (also allowing for lower ruthenium contamination in crude metathesis products) and improves the overall green angle of olefin metathesis.

Well-Defined Chiral Copper NHC Complex in the Asymmetric Conjugated ß-Borylation and One-Pot Metathesis-Asymmetric ß-Borylation Reactions.

Highly stereoselective conjugate ß-borylation, using a new chiral NHC-based copper catalyst, has been achieved. The chiral NHC copper complex was prepared in gram scale and showed high enantioselectivity and activity (up to 10 000 turnovers at 100 ppm of catalyst loading). This method was employed in the synthesis of a chiral ß-borylated ester from simple unconjugated alkenes though an unprecedented one-pot cross metathesis-asymmetric borylation sequence.

Forged and fashioned for faithfulness-ruthenium olefin metathesis catalysts bearing ammonium tags.

In this article, the synthesis and applications of selected ammonium tagged Ru-alkylidene metathesis catalysts were described. Because of the straightforward synthesis, the first generation of onium-tagged catalysts have the ammonium group installed in the benzylidene ligand. Such catalysts usually give relatively pure metathesis products, and are used in polar solvents and water, or immobilised on various supports. Later, catalysts tagged in the N-heterocyclic carbene ligand (NHC) were developed to offer higher stability and even lower metal contamination levels. Due to minimal leaching, the non-dissociating ligand tagged systems were successfully immobilised on various supports, including zeolites and Metal Organic Frameworks (MOFs) and used in batch and in continuous flow conditions.

Synthesis of Selectively Substituted or Deuterated Indenes via Sequential Pd and Ru Catalysis.

A strategy for the synthesis of functionalized indenes is presented. The readily available substituted phenols are used as starting materials in the reaction sequence composed of Pd-catalyzed Suzuki coupling and Ru-catalyzed ring-closing metathesis, thus representing a practical method for the controlled construction of functionalized indene derivatives. The methodology has been successfully applied to a broad range of substrates, producing substituted indenes in excellent yields. This approach is also utilized for the synthesis of substituted indenes selectively deuterated in position 3, which are rare in literature.

Mild Functionalization of Tetraoxane Derivatives via Olefin Metathesis: Compatibility of Ruthenium Alkylidene Catalysts with Peroxides.

An easy and mild functionalization method of tetraoxane derivatives via olefin metathesis is reported. This reaction offers a new method to afford fully functionalized tetraoxanes in high yields. This method is also utilized in the functionalization of bioactive compounds.

Studies towards the synthesis of bielschowskysin. Construction of the highly functionalized bicyclo[3.2.0]heptane segment.

A stereocontrolled approach for the construction of a highly functionalized bicyclo[3.2.0]heptane derivative embodying the bridged lactone present in the diterpene bielschowskysin is reported. The key step involves a stereoselective Cu(I)-catalyzed [2 + 2] photocycloaddition of a 1,6-diene embedded in a sugar derivative.