We report on facile hydrothermal synthesis of 2H and 1T/2H mixed-phase MoS2 nanosheets using different organic sulfur precursors with varying release tendencies. demonstrated direct solar light-driven photocatalysis...

Triangular Heisenberg antiferromagnets are prototypes of geometric frustration, even if for nearest-neighbor interactions quantum fluctuations not usually strong enough to destroy magnetic ordering: stronger frustration is required stabilize a spin-liquid phase. On the basis static magnetization and electron spin resonance measurements, we demonstrate emergence ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{j}}_{\text{eff}}=\frac{1}{2}$ moments in triangular-lattice magnet...

Abstract Quantum‐chemical calculations are performed at the semiempirical Valence‐Bond/Hartree–Fock level on model 1D aggregates to assess electronic structure pentacene/C 60 heterojunctions. We show that asymmetry of electrostatic potential interface profoundly impacts energy landscape explored by charges, as they move away from interface. Depending orientation pentacene molecules with respect interface, effects may favor either charge recombination or separation process. © 2012 Wiley...

An ultrasharp photoluminescence line intimately related to antiferromagnetic order has been found in ${\mathrm{NiPS}}_{3}$, a correlated van der Waals material, opening prospects for magneto-optical coupling schemes and spintronic applications. Here we unambiguously clarify the singlet origin of this excitation, confirming its roots spin structure. Based on comprehensive investigation electronic structure using angle-resolved photoemission $q$-dependent electron energy loss spectroscopy as...

The electronic and magnetic properties of Mn coordinated to 1,2,4,5-tetracyanobenzene (TCNB) in the Mn-TCNB 2D metal-ligand networks have been investigated by combining scanning tunneling microscopy X-ray circular dichroism (XMCD) performed at low temperature (3 K). When formed on Au(111) Ag(111) substrates display similar geometric structures. Magnetization curves reveal ferromagnetic (FM) coupling sites with single-ion anisotropy energies, but different constants. Low-temperature XMCD...

A judicious analysis of previously published experimental data leads one to conclude that the ground state iron(II) phthalocyanine is an orbitally degenerate spin triplet $a_{1g}^2 e_g^{\uparrow\downarrow\uparrow} b_{2g}^{\uparrow}$ ($^3E_g$). The ligand field parameters, in relation Racah's $C$, are approximately as follows: $B_{20}/C=0.84$, $B_{40}/C=0.0074$. uniqueness this result demonstrated by means a special diagram $B_{20}/C-B_{40}/C$ plane (under additional conditions...

In conventional analyses of g approximately 5 signals given by [4Fe-4S](+) clusters with S = 3/2, the effective values that cannot be measured in electron paramagnetic resonance (EPR) spectrum are deduced from rhombograms calculated assuming matrix is isotropic g(x) g(y) g(z) 2.00. We have shown when two low-field peaks corresponding to Kramers doublets visible spectrum, a new, independent piece information about system can obtained studying temperature dependence ratio area under these...

We report the results of a comprehensive study exchange interactions in Co-doped ZnO using inelastic neutron scattering, electron paramagnetic resonance, and magnetic property measurements. In particular, we observe an unprecedentedly strong spatial anisotropy two nearest-neighbor exchanges, ${J}^{(1)}=\ensuremath{-}25.6\ifmmode\pm\else\textpm\fi{}0.3$ K ${J}^{(2)}=\ensuremath{-}8.5\ifmmode\pm\else\textpm\fi{}0.4$ K, along with distant-neighbor $J$ values ferromagnetic sign. argue that...

Pure and cobalt-doped zinc oxide aligned nanorods have been grown by the low-temperature (90 °C) aqueous chemical method on amorphous ZnO seed layer, deposited a sapphire substrate. High crystallinity of these objects is demonstrated electron paramagnetic resonance investigation at liquid helium temperature. The successful incorporation Co2+ ions in substitution Zn2+ ones matrix has also confirmed. A drastic reduction intrinsic core defects observed Co-doped samples, which enhances...

Planar metal–organic networks are highly promising materials due to their modular nature and wide-ranging possible applications from spintronics up biosensing. Spin state transitions connect local magnetic properties with structural modifications. In this paper, we report on ab initio calculations for two planar networks, the Fe-phthalocyanine (Pc) polymer its precursor material Fe-tetracyanobenzene (TCNB). The spin-polarized generalized gradient approximation density functional theory an...

Cobalt-doped ZnO microwires have been grown by the optical furnace method with Co concentration in range 0–5%. The high crystallinity of these objects is demonstrated use electron paramagnetic resonance (EPR), which Co2+ ions serve as magnetic probes. spin state isolated impurities and their location host crystal are addressed EPR, well coupling constant between non-nearest Co2+–Co2+ neighbors. Eight distant pairs detected, among two confirmed to be ferromagnetic. problem localization...

Exchange integrals between nearest-neighbor (NN) transition metal ions in II-VI diluted magnetic semiconductors (DMSs) are calculated within a local superexchange model, which includes orbital-dependent transfer, on-site Coulomb repulsion and Hund's exchange $3d$ electrons, ligand field effects. This extended model gives quantitative account for the available experimental data on NN constants all DMS family (wurtzite zinc-blende) doped by cobalt or manganese. As expected, obtained...

Zinc oxide (ZnO) nanorods grown by the low-temperature (90 °C) aqueous chemical method with different cobalt concentration within synthesis solution (from 0% to 15%), are studied electron paramagnetic resonance (EPR), just above liquid helium temperature. The anisotropic spectra of substitutional Co2+ reveal a high crystalline quality and orientation NRs, as well probable presence secondary disordered phase ZnO:Co. analysis EPR indicates that disappearance native core-defect (CD) at...

We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 °C). Two different mixing methods of solutions were investigated for samples. The synthesized samples compared NRs regarding Co incorporation crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed substitution Co2+ inside NRs, giving a highly anisotropic magnetic signal. Zn2+ by was...

Motivated by recent developments in spintronics, we propose an explanation of the single-ion anisotropy Mn-doped diluted magnetic semiconductors using as example high-quality ZnO:Mn thin films for which $X$-band electron-paramagnetic-resonance studies were performed. We derive analytic formula axial parameter $D$ and prove its validity exact diagonalization method. demonstrate a quantitative agreement between experimental data our model. These results bring insights into long-standing problem solids.

A method is developed to calculate the ligand field (LF) parameters and multiplet spectra of local magnetic centers with open $d$ $f$ shells in solids a parameter-free way. This proceeds from density functional theory employs Wannier projections nonmagnetic band structures onto or orbitals. Energies multiplets optical, as well x-ray are determined by exact numerical diagonalization Hamiltonian describing Coulomb, LF, spin-orbit interactions. The tested for several $3d$ $5f$ compounds which...

The effects of white-light irradiation on ∼ 20 nm diameter ZnO nanoparticles are investigated by means electron paramagnetic resonance, near liquid-nitrogen and liquid-helium temperatures.Under dark conditions, usual core-and surface-defects detected, respectively at g = 1.960 2.003.Under illumination, the core-defect signal intensity is strongly increased, which to be correlated light-induced conductivity's augmentation.Beside, a four-lines structure appears, with same gravity center as...

The combination of nuclear and electron magnetic resonance techniques, in pulse continuous wave regimes, is used to unravel the nature features light-induced state arising at surface chemically prepared zinc oxide nanoparticles (NPs) occurring under 120 K when subjected a sub-bandgap (405 nm) laser excitation. It shown that four-line structure observed around g ∼ 2.00 as-grown samples (beside usual core-defect signal 1.96) arises from surface-located methyl radicals (•CH3), originating...

We propose an alternative explanation, as compared to one reported in the literature, experimentally observed spatial anisotropy $\ensuremath{\xi}=\ensuremath{\Delta}{J}_{1}/{J}_{1}^{\mathrm{in}}$ ($\ensuremath{\Delta}{J}_{1}={J}_{1}^{\mathrm{in}}\ensuremath{-}{J}_{1}^{\mathrm{out}}$) of nearest neighbor exchange integral ${J}_{1}$ Mn-doped semiconductors with wurtzite structure. show that main contribution $\ensuremath{\xi}$ is ferromagnetic and comes from a looped path which involves two...

Cobalt-doped ZnO nanoparticles (NPs) with different Co concentrations are investigated by means of $X$- and $Q$-band electron spin resonance (ESR) near liquid-helium temperature in both parallel perpendicular modes. The high crystal quality the NPs allows for hyperfine-structure resolution within single ${\mathrm{Co}}^{2+}$ ions' ESR powder spectra. Depending on cobalt concentration, common additional weak lines detected which here demonstrated to arise from some high-spin pairs a distance...

The spectral dependence of the light‐induced magnetic states generated in zinc oxide nanoparticles by illumination during an electron paramagnetic resonance (EPR) experiment is studied for three incident light wavelengths (451, 405, and 370 nm). minimal wavelength excitation found to be visible violet region, very close 405 nm all EPR lines. This points a relationship between their originating centers, despite difference dynamics previously revealed saturation recovery measurements. study...

The single ion magnetic anisotropy of S-state transition metal ions (3d5) in wurtzite diluted semiconductors (DMS) is studied from a microscopic point view. Starting hamiltonian including Coulomb, spin–orbit and effective crystal field interactions, the axial spin parameter calculated by using an exact diagonalization method. Application to some Mn-doped DMS validates model.

We demonstrate that the low temperature synthesis chemical route can be utilized to control functionality of zinc oxide (ZnO) nanoparticles (NPs) and nanorods (NRs) for optical magneto-optical performance. Different structural, optical, electro- results will displayed analyzed. In first part, we show how high quality ZnO NPs efficient photodegradation using ultra-violet radiation. second part present our recent on core defects in cobalt doped NR. Here by electron paramagnetic resonance (EPR)...