Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH10, encounters a serious complication because of the large upper critical magnetic field HC2(0), exceeding 120–160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH10: each at% of Nd causes a decrease in TC by 10–11 K, helping to control the critical parameters of this compound. Strong pulsed magnetic fields up to 68 T are used to study the Hall effect, magnetoresistance, and the magnetic phase diagram of ternary metal polyhydrides for the first time. Surprisingly, (La,Nd)H10 demonstrates completely linear HC2(T) ∝ |T – TC|, which calls into question the applicability of the Werthamer–Helfand–Hohenberg model for polyhydrides. The suppression of superconductivity in LaH10 by magnetic Nd atoms and the robustness of TC with respect to nonmagnetic impurities (e.g., Y, Al, C) under Anderson's theorem gives new experimental evidence of the isotropic (s‐wave) character of conventional electron–phonon pairing in lanthanum decahydride.

9MnGeO3 single crystal samples have been synthesized by optical zonal melting and spon-10 taneous crystallization. X-ray crystal analysis showed the first sample to be a two-phase one with 11 phase ratio: 17% -monoclinic C2/c and 83% -orthorhombic Pbca; the phase ratio of the second 12 sample was unknown. Raman spectra have been produced for these samples. Lattice dynamics 13 has been simulated and polarization dependencies of lines' intensities have been analyzed to in-

Composite materials fabricated by annealing of nonsuperconducting ceramics La 2 CuO 4 and La 1.56 Sr 0.44 CuO 4 at 910° C during various time are investigated. Areas of superconducting La 1.85 Sr 0.15 CuO 4 phase arises at boundaries of contacting nonsuperconducting granules. The volume fraction of the superconducting phase increases with increasing the annealing time. A model describing the magnetic and transport properties of the samples at low magnetic fields is constructed. The magnetotransport characteristics of obtained samples at low magnetic fields (~ 100 Oe) are defined by a weak links network formed by superconducting areas. At high fields behavior of the system is defined by a magnetization of the disconnected superconducting islands. The average size of the superconducting areas has been estimated from an extended critical state model.

Correlations between the direct and inverse magnetoelectric effects in orthorhombic DyMnO3 single crystals have been investigated. In the inverse magnetoelectric effect, the magnetic moment of the crystal appears to have a contribution that is sinusoidal oscillating in ac electric fields below the temperature TFE of ferroelectric phase transition. The first and the second harmonics of the inverse magnetoelectric effect are clearly detected. The magnetoelectric susceptibilities α and β, corresponding to first and second harmonics, are found to correlate with the derivative of polarization with respect to the magnetic field. The influence of the magnetic and electric regimes during cooling on magnetoelectric effects has also been studied. The maximum change in the magnetic moment of a sample under the action of electric fields is observed under the same (T, H) conditions as the rotation of the spontaneous polarization vector from the crystallographic c direction to the a axis in the magnetic field H || b.