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A planar side-gate device for field effect with a La0.67Ba0.33MnO3 channel on a SrTiO3 substrate is fabricated by means of the voltage-biased tip of an atomic force microscope. The peculiar geometry and the high dielectric permittivity of the substrate enhance the channel resistance modulation up to 20% at low temperature by a gate voltage of ±40 V. Moreover, a reversible shift by 1.3 K of the metal–insulator transition temperature (TMI) by field effect is observed. The signs of the changes of resistance and TMI both depend on the sign of the gate voltage, as expected for pure field effect; in particular, the TMI is raised (lowered) by accumulating (depleting) holes in the channel.

We present a simple method allowing the determination of the degree of texture of superconducting grains inside Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O10+x tapes from a set of magnetic measurements. This procedure is based on the considerable anisotropy existing between the in-plane and out-of-plane critical current densities of individual crystallites in Bi-based superconducting compounds. By this method, we have monitored the evolution of the precursor Bi2Sr2CaCu2O8+y grain texturing in unreacted multifilamentary tapes in the course of the cold rolling deformation process. Evidence for anisotropic texturing, i.e., different longitudinal and transversal angle with respect to the rolling direction, has been observed. The accuracy of the method is discussed and the results compared with the current literature.

We show that the growth of the heterostructure LaGaO3 /SrTiO3 yields the formation of a highly conductive interface. Our samples were carefully analyzed by high resolution electron microscopy, in order to assess their crystal perfection and to evaluate the abruptness of the interface. Their carrier density and sheet resistance are compared to the case of LaAlO3 /SrTiO3 and a superconducting transition is found. The results open the route to widening the field of polar-nonpolar interfaces, pose some phenomenological constrains to their underlying physics and highlight the chance of tailoring their properties for future applications by adopting suitable polar materials.

In this letter we present the effect of neutron irradiation up to fluences of 3.9 1019 n/cm2 on the superconducting properties of MgB2. In order to obtain a disorder structure homogeneously distributed, the experiment was carried out on bulk samples prepared with the 11B isotope. Up to fluences of 1018 n/cm2 the critical temperature is slightly diminished (36 K) and the superconducting properties are significantly improved; the upper critical field is increased from 13.5 T to 20.3 T at 12 K and the irreversibility field is doubled at 5 K. For larger neutron fluences the critical temperature is suppressed down to 12 K and the superconducting properties come out strongly degraded.

High electron mobility is measured down to low temperature in epitaxial ZnO thin films deposited on (110) oriented strontium titanate substrates. Electron mobility is evaluated by both magnetoresistance and resistivity-Hall effect data. Values up to 400cm2∕Vs are found below 50 K in epitaxial thin films grown by a two-step method: first a 100-nm-thick ZnO relaxing layer is deposited on the SrTiO3 (110) substrate at relatively low temperature (550–600 °C) and then the deposition temperature is raised up to 800 °C for the growth of a second ZnO layer. Reflection high energy electron diffraction analysis during the deposition, ex situ x-ray diffraction and AFM morphology studies performed separately on each layer reveal that the first layer grows in a quasi-two-dimensional mode while the increased temperature in the second step improves the crystalline quality of the film. The integration of ZnO transparent semiconductor with high-k dielectric perovskite substrates may lead to a wide variety of new electroni...