The in-plane resistivity, in-plane absolute thermopower, and upper critical field measurements are reported for single-crystal samples of YNi 2 B 2 C and LuNi 2 B 2 C superconductors. The in-plane resistivity shows metallic behavior and varies approximately linearly with temperature near room temperature ͑RT͒ but shows nearly quadratic behavior in temperature at low temperatures. The YNi 2 B 2 C and LuNi 2 B 2 C single-crystal samples exhibit large transverse magnetoresistance ͑Ϸ6-8 % at 45 kOe͒ in the ab plane. The absolute thermopower S(T) is negative from RT to the superconducting transition temperature T c. Its magnitude at RT is a few times of the value for a typical good metal. S(T) is approximately linear in temperature between Ϸ150 K and RT. Extrapolation to Tϭ0 gives large intercepts ͑few V/K͒ for both samples suggesting the presence of a much larger ''knee'' than would be expected from electron-phonon interaction renormalization effects. The upper critical fields for H parallel and perpendicular to the c axis and the superconducting parameters derived from it do not show any anisotropy for the YNi 2 B 2 C single-crystal samples in agreement with magnetization and torque magnetometry measurements, but a small anisotropy is observed for the LuNi 2 B 2 C single crystals. The analysis shows that these are moderately strong-coupling type-II superconductors ͑similar to the A-15 com-pounds͒ with a value of the electron-phonon coupling parameter ͑0͒ approximately equal to 1.2 for YNi 2 B 2 C and 1.0 for LuNi 2 B 2 C, the Ginzburg-Landau coherence length ͑0͒ approximately equal to 70 Å, and H c2 (0)ϳ60-70 kOe. The temperature dependence of the upper critical field shows a positive curvature near T c in disagreement with the Werthamer, Helfand, Hohenberg, and Maki ͑WHHM͒ theory but in agreement with a recent solution of the Gor'kov equation using a basis formed by Landau levels ͑Bahcall͒; however, the data show a severe disagreement between the observed low-temperature behavior of H c2 (T) and that predicted either by WHHM or Bahcall's expressions. ͓S0163-1829͑97͒06413-8͔

Large high-purity single crystals of FeTiO3 with ilmenite structure have been grown from a stoichiometric melt of Fe2O3 and TiO2 under an inert atmosphere using the modified Czochralski technique. Susceptibility and x-band paramagnetic resonance studies have been performed. Susceptibility measurements indicate a Néel temperature ∼59 K. The paramagnetic resonance spectrum for magnetic field perpendicular to the crystal c axis consists of a portion of a single, very intense approximately Lorentzian absorption line with its peak at about 600 G and half width at half maximum almost 1200 G. The absorption extends to zero magnetic field. For magnetic field approximately parallel to the c axis, the paramagnetic absorption is much smaller and may be considered a superposition of two approximately Lorentzian line shapes. The magnetic resonance measurements indicate a weak temperature dependence and large angular anisotropy.

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We present a study of anisotropy of transport and magnetic properties in a La1−xCaxMnO3 (x ≈ 1/3) film prepared by pulsed-laser deposition onto a LaAlO3 substrate. We found a non-monotonic dependence of magnetoresistance (MR) on magnetic field H for both H perpendicular and parallel to the film plane but perpendicular to the current. In the longitudinal geometry (when H is parallel to both the current and the film plane) the MR was negative at all fields below 20 kOe, as expected for colossal-magnetoresistance manganites. This rather complex behavior of MR manifests itself at rather low temperatures, far below the Curie temperature Tc, which was close to room temperature. Two main sources of MR anisotropy in the film have been considered in the explanation of the results: (1) the existence of preferential directions of magnetization (due to strains stemming from the lattice film-substrate mismatch or other reasons); (2) dependence of resistance on the angle between current and the magnetization, which is inherent in ferromagnets. The transport and magnetic properties of the film correspond well to this view. In particular, the following angle dependence of MR is found: R(θ)/R(0) = 1 + δan(T, H) sin 2 θ (where θ is the angle between the field and current directions in the plane normal to the film but parallel to the current). The temperature and magnetic field dependences of δan(T, H) were recorded and analyzed. A clear magnetization anisotropy, that generally favors the magnetization in the film plane is also found. At the same time the recorded magnetization curves (as well as the MR data) indicate, that the film crystal structure should be inhomogeneous in such a way that various parts of the films have non-identical magnetic properties (with different directions of spontaneous magnetization). This hypothesis is supported by X-ray diffraction which revealed that the film is inhomogeneous in strain, lattice parameter and lattice orientation. This peculiar macroscopic-scale disorder is caused by a film-substrate interaction. The possible reasons for formation of such structure and its effect on MR anisotropy are considered.

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