Conductivity, weak ferromagnetism and charge instability in α−MnS\alpha-MnS single crystal

The temperature dependence of resistivity, magnetization and electron-spin resonance of the $\alpha- MnS$ single crystal were measured in temperature range of $5 K < T < 550 K$. Magnetization hysteresis in applied magnetic field up to 0.7 T at $T=5 K, 77 K, 300 K$, irreversible temperature behavior of magnetization and resistivity were found . The obtained data were explained in terms of degenerate tight binding model using random phase approximation. The contribution of holes in $t_{2g}$ and $e_g$ bands of manganese ions to the conductivity, optical absorbtion spectra and charge instability in $\alpha -MnS$ were studied. Charge susceptibility maxima resulted from the competition of the on-site Coulomb interaction between the holes in different orbitals and small hybridization of sub-bands were calculated at $T=160 K, 250 K, 475 K$.Comment: 6 pages, 12 figure

Reply to Comment on "Competition between helimagnetism and commensurate quantum spin correlations in LiCu2O2"

Exchanged interactions in recently observed helical structure in LiCu2O2 is probed by inelastic neutron scattering. The main conlusions of Refs. [1,2] are confirmed: nn interactions in single chains are ferromagnetic and frustrated by nnn antiferromagnetic ones. However, in apparent disagreement with Refs. [1,2] double-chain interactions are found to be of the same order of magnitude as the single-chain ones, and thus involved in the frustration mechanism. [1] Drechsler et al., cond-mat/0411418. [2] A. Gippius et al. Phys. Rev. B 70 (2004), R01426; cond-mat/0312576.Comment: Reply to the Comment by S.-L. Drechsler, J. Malek, J. Richter, A.S. Moskvin, A.A. Gippius, H. Rosner, cond-mat/041141

Coexistence of dimerization and long-range magnetic order in the quantum antiferromagnetic compound LiCu2O2: inelastic light scattering study

Raman scattering studies of the frustrated spin chain system LiCu$_{2}$O$_{2}$ are reported. Two transitions into a magnetically ordered phase (taken place at temperatures $\sim$ 9 K and $\sim$ 24 K) have been confirmed from the analysis of optical properties of the samples. Interestingly, two different magnetic excitations, seen at 100 and 110 cm$^{-1}$ in the magnetically ordered phase superimpose each other independently, indicating a coherent coexistence of long-range magnetic order and dimerization. The observed phenomenon is attributed to magnetostructural peculiarities of LiCu$_{2}$O$_{2}$ leading to the intrinsic presence of nonmagnetic impurities on a nanometer scale. Furthermore, magnetic impurities play a significant role in driving the transition from an incommensurate state to a N\'{e}el ordered one at 9 K.Comment: 5 pages, 4 figures. submitted to PRB; Manuscript is improve

Exchange Interactions in the Cr3+–Cr3+ Ion Pair in the ABO3 (A = Ga, In, Sc) Diamagnetic Matrix (Обменные взаимодействия в паре ионов Cr3+−Cr3+ в диамагнитной матрице ABO3 (A = Ga, In,Sc))

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The exchange interactions in the Cr3+–Cr3+ ion pairs in the isostructural ABO3 (A = Ga, In, Sc) diamagnetic compounds have been examined using the magnetic resonance technique. The values of bilinear and biquadratic exchange interactions have been determined. It is shown that the biquadratic exchange in the Cr3+–Cr3+ pair in these compounds is caused by the exchange striction

Electron Paramagnetic Resonance of Cr3+ Ions in ABO3 (A = Sc, Lu, In) Diamagnetic Crystals

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A magnetic resonance method is applied to the investigation of a number of isostructural diamagnetic compounds ABO3 (A = Sc, Lu, In) with small additions of Cr3+ ions (S = 1/2) sufficient to observe single- ion spectra. It is shown that the resonance spectra for isolated Cr3+ ions can be described to a good accuracy by the ordinary axial spin Hamiltonian for 3d ions in octahedral oxygen environment. The parameters of the spin Hamiltonian are determined. It is established that Cr3+ ions in these crystals are characterized by easy-axis-type anisotropy

Electron Paramagnetic Resonance of Cr3+ Ions in ABO3 (A = Sc, Lu, In) Diamagnetic Crystals

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A magnetic resonance method is applied to the investigation of a number of isostructural diamagnetic compounds ABO3 (A = Sc, Lu, In) with small additions of Cr3+ ions (S = 1/2) sufficient to observe single- ion spectra. It is shown that the resonance spectra for isolated Cr3+ ions can be described to a good accuracy by the ordinary axial spin Hamiltonian for 3d ions in octahedral oxygen environment. The parameters of the spin Hamiltonian are determined. It is established that Cr3+ ions in these crystals are characterized by easy-axis-type anisotropy

Magnetic resonance studies of mixed chalcospinel CuCr2SxSe4−x (x = 0; 2) and CoxCu1−xCr2S4 (x = 0.1; 0.2) nanocrystals with strong interparticle interactions

Magnetic resonance characteristics of mixed chalcospinel nanocrystals CuCr2SxSe4−x (x = 0 and 2) and CoxCu1−xCr2S4 (x = 0.1 and 0.2) have been investigated. It has been established based on TEM, SEM and resonance data that all the samples contain both blocks with sizes from 1 to 50 m of compacted nanosized crystallites and individual nanoparticles with sizes from 10 to 30 nm. The studies provide evidence of strong interparticle interaction in all the samples leading to high values of the blocking temperature. Magnetic dipolar field arise in the boundary regions of interacting adjacent nanocrystals below the blocking temperature. This results in inhomogeneous broadening of the magnetic resonance spectrum along with appearance of additional absorption lines. With increase in magnetic anisotropy at low temperatures, a shift of the resonance field along with line broadening are observed for all the studied compounds due to freezing of the moments in the nanoparticles, both in the individual and compacted ones. A gapped characteristic of the resonance spectrum is established below the freezing temperature Tfr, with the energy gap defined by the averaged magnetic anisotropy . Anionic substitution of sulfur by selenium results in a decrease in the magnetic anisotropy. In contrast, cationic substitution of copper by cobalt increases the magnetic anisotropy due to a strong contribution from the latter ion

Magnetic resonance in a gallium-doped Cu-Cr-S structure

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A layered Cu–Cr–S structure doped with Ga ions and consisting of single-crystal CuCrS2 layers, embedded with thin plates of spinel phases CuCr2S4 and CuGaxCr2–xS4, has been studied using the magnetic resonance and magnetic susceptibility methods. The Curie temperature and the saturation magnetization of the spinel phases of the samples have been determined. The spinel phase layer thickness has been estimated

Magnetic resonance in a gallium-doped Cu-Cr-S structure

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A layered Cu–Cr–S structure doped with Ga ions and consisting of single-crystal CuCrS2 layers, embedded with thin plates of spinel phases CuCr2S4 and CuGaxCr2–xS4, has been studied using the magnetic resonance and magnetic susceptibility methods. The Curie temperature and the saturation magnetization of the spinel phases of the samples have been determined. The spinel phase layer thickness has been estimated