The asymmetry between electron and hole doping in high critical-temperature superconducting (HTS) cuprates is key information for the understanding of Cooper pair formation mechanisms. Despite ...intensive studies on different cuprates, a comprehensive description of related magnetic and charge excitations is still fragmentary. In the present work, artificial cuprates were used to cover the entire phase diagram within the same HTS family. In particular, Cu L3-edge resonant inelastic x-ray scattering (RIXS) measurements were performed on artificial n- and p-type infinite layer (IL) epitaxial films. Beside several similarities, RIXS spectra show noticeable differences in the evolution, with doping level, of magnetic and charge intensity and damping. Compatible trends can be found in spectra measured on bulk cuprates, as well as in theoretical calculations of the spin dynamical structure factor S(q,ω). The findings give a deeper insight into the evolution of collective excitations across the cuprate phase diagram, and on underlying general features, only connected to the doping type. Moreover, they pave the way to the exploration of general properties of HTS physics over a broad range of conditions, by means of artificial compounds not constrained by the thermodynamic limitations governing the chemical stability of bulk materials.
We have studied the low temperature electrical transport properties of LaxSr1−xCuO2 thin films grown by oxide molecular beam epitaxy on (1 1 0) GdScO3 and TbScO3 substrates. The transmission electron ...microscopy measurements and the x-ray diffraction analysis confirmed the epitaxy of the obtained films and the study of their normal state transport properties, removing the ambiguity regarding the truly conducting layer, allowed to highlight the presence of a robust hidden Fermi liquid charge transport in the low temperature properties of infinite layer electron doped cuprate superconductors. These results are in agreement with recent observations performed in other p and n doped cuprate materials and point toward a general description of the superconducting and normal state properties in these compounds.
We here report on the occurrence of strong orbital order driven by off-stoichiometry in oxide manganile films. Multiple-electronic-valence Mn ions are possibly substituted into the perovskite atomic ...A site (namely, A-site manganites). By combining state-of-the-art synchrotron ultrafine spectroscopies, we did provide evidence of a high ferromagnetic metallic state together with a strong orbital order of Mn ions, despite that the kinetic energy of the free charge carriers should prevent long-range orbital order. By varying the total amount of Mn ions at the perovskite A site, a specific orbital order (either in-plane or out-of-plane) can be determined.
SrRuO3 is a strong itinerant ferromagnet showing many features of 'bad metals' together with Fermi liquid behavior at very low temperature. The intriguing magnetic and transport properties of SrRuO3 ...are tightly related to structure, as commonly observed in transition metal oxides. Here we report on the correlation of structural parameters (lattice constant and surface roughness) with the critical behavior of resistivity at the Curie point in SrRuO3 thin films deposited on (001) SrTiO3 by PLD. By varying the deposition conditions we were able to obtain a wide variety of structural properties in our samples, thus allowing us to perform a systematic study. Our analysis demonstrates the direct correlation between the critical temperature TP and the lattice out-of-plane parameter. Furthermore, the value of the critical exponent λ is proved to be a good physical parameter to quantify the microscopic order of SrRuO3 samples.
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