http://dspace.nbuv.gov.ua:80/handle/123456789/128442 2026-04-26T09:22:18Z http://dspace.nbuv.gov.ua:80/handle/123456789/130241 Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ Gnezdilov, V.P.; Pashkevich, Yu. G.; Yeremenko, A.V.; Lemmens, P.; Güntherodt, G.; Tranquada, J.M.; Buttrey, D.J.; Nakajima, K. We describe the results of electronic Raman scattering experiments in two differently doped single crystals of La₂₋xSrxNiO₄ (x=0.225 and 1/3). In B₁g symmetry a crossover from weakly interacting to pseudogap-like behavior is observed at a charge-ordering temperature Tco. In B₂g symmetry a redistribution of electronic continua with decreasing temperature is accompanied by a loss of spectral weight below Tco in the low-frequency region due to opening of a pseudogap. The slope of the Raman response at vanishing frequencies is investigated, too. Its temperature behavior in B₂g symmetry, which predominantly selects charge carriers with momenta along the diagonals of the NiO₂ bonds, provides clear evidence for one-dimensional charge transport in the charge-ordered phase. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/130240 Spin-phonon interaction and mode softening in NiF₂ Lockwood, D.J. The temperature dependence of the four Raman-active phonons in NiF₂ is investigated at temperatures above and below the antiferromagnetic ordering temperature of TN=73 K. All four modes exhibit distinct anomalies in their intensities and frequencies near TN due to spin–phonon coupling. The phonon linewidths also exhibit weak anomalies. From the temperature dependences of the phonon frequencies, estimates are made of the spin–phonon coupling coefficients. The B1g phonon exhibits anomalous mode softening with decreasing temperature from 300 K to TN. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/130239 Elementary excitations in solid oxygen Freiman, Yu. A.; Jodl, H.J. Theoretical results on lattice excitations in solid oxygen at equilibrium vapor pressure are reviewed with the emphasis on the behavior of phonons, librons, and magnons in the orientationally and magnetically ordered α phase. Results on the magnetooptics of solid oxygen and their impact on the advancement of magnetic studies of solid oxygen are briefly reviewed. Some results under discussion are new: among these are theoretical results on the magnon heat capacity, the analysis of the behavior of librons at the α–β transition, and anisotropy of the magons spectrum. 2002-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/130238 On the transverse magnetization of the anisotropic superconductor 2H-NbSe₂ Sirenko, V.A.; Makedonska, N.I.; Shabakayeva, Yu. A. Torque measurements were performed on a high-quality single crystal of the uniaxial superconductor 2H-NbSe₂ in a tilted magnetic field 0–200 kG, in the temperature range 1.5–4.2 K. The transverse component of the absolute magnetization was derived in a magnetic field directed at an angle of 77° to the axis of anisotropy, and its field dependence was analyzed in a reversible domain of the mixed state. The penetration depth and anisotropy characteristics were obtained for the sample under study. 2002-01-01T00:00:00Z