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

Magnetic Phase Transitions in the double spin-chains compound LiCu2O2\rm LiCu_2O_2

We report high-resolution x-ray diffraction, muon-spin-rotation spectroscopic and specific heat measurements in the double spin-chains compound $\rm LiCu_2O_2$. The x-ray diffraction results show that the crystal structure of $\rm LiCu_2O_2$ ~is orthorhombic down to T=10K. Anisotropic line-broadening of the diffraction peaks is observed, indicating disorder along the spin chains. Muon spin relaxation and specific heat measurements show that $\rm LiCu_2O_2$ \~undergoes a phase transition to a magnetic ordered state at $\rm T_1\sim24K$. The specific heat data exhibits a second $\rm \lambda$-like peak at $\rm T_2\sim22.5 K$, which increases with increasing magnetic field similarly way to that found in spin-ladder compounds.Comment: 6 pages, 6 fifures, to appear in Physica

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 Single Crystals of Yttrium Aluminum Borate YAl3(BO3)4

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Single crystal of yttrium aluminum borate YAl3(BO3)4 doped with chromium ions (1 at.%) was studied using electron paramagnetic resonance spectroscopy. It is shown that chromium ions introduced into the sample occupy yttrium ion sites in the crystal structure. The parameters of the spin Hamiltonian of Cr3+ ions in the YAl3(BO3)4 matrix are determined at different temperatures. The sign of the fine structure parameter D allows the conclusion that the chromium ions in YAl3(BO3)4 single crystals have an easy-plane 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

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 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