The Role of CuO Chain Length on Superconductivity Emergence in YBa2Cu3O6.30

The authors investigate the tetragonal(T)-orthorhombic(O) transient zone of YBa2Cu3O6+x, in a comparative way on pair samples one of which is produced by deintercalation [D] and the other by intercalation [I] of intrinsic oxygen in the basal Cu(1)Ox plane and having the same oxygen content (k) and thermal history. Resistive and electron diffraction measurements, performed on [D]k-[I]k pairs within the composition range 0.28 ≤ k ≤ 0.32, are reported. Direct evidence is provided that the T-OII transient is a structural and electronic two phase region characterized by the (T+OII)[D]0.30 non-superconducting (non-SC) and (OII+OIII*)[I]0.30 superconducting (SC) phases. The OII superstructure represents the minority component of [D]0.30 phase and the majority one of [I]0.30 and OIII* is a new orthorhombic anti-OIII superstructure. The nature of the non-SC and SC behaviours has been comparatively investigated by NQR analysis at the T-OII borderline. The evaluated different values of the average chain lengths emphasize the role of the Cu-O chain length on the hole doping efficiency in YBCO at constant oxygen content

Zeeman perturbed nuclear quadrupole resonance investigation of orbitally ordered KCuF3

We investigated the electric field gradient tensor at the Cu nuclei by Zeeman perturbed nuclear quadrupole resonance in orbitally ordered KCuF3. Our data show the presence of two inequivalent crystallographic sites with distinct orientations of the copper wave function, compatibly with the proposed orbital order for this compound. An unusual behaviour of the paramagnetic NQR signal at the Néel transition is reported

The Role of CuO Chain Length on Superconductivity Emergence in YBa2Cu3O6.30

The authors investigate the tetragonal(T)-orthorhombic(O) transient zone of YBa2Cu3O6+x, in a comparative way on pair samples one of which is produced by deintercalation [D] and the other by intercalation [I] of intrinsic oxygen in the basal Cu(1)Ox plane and having the same oxygen content (k) and thermal history. Resistive and electron diffraction measurements, performed on [D]k-[I]k pairs within the composition range 0.28 ≤ k ≤ 0.32, are reported. Direct evidence is provided that the T-OII transient is a structural and electronic two phase region characterized by the (T+OII)[D]0.30 non-superconducting (non-SC) and (OII+OIII*)[I]0.30 superconducting (SC) phases. The OII superstructure represents the minority component of [D]0.30 phase and the majority one of [I]0.30 and OIII* is a new orthorhombic anti-OIII superstructure. The nature of the non-SC and SC behaviours has been comparatively investigated by NQR analysis at the T-OII borderline. The evaluated different values of the average chain lengths emphasize the role of the Cu-O chain length on the hole doping efficiency in YBCO at constant oxygen content

Proximity effects induced by a gold layer on La0.67Sr0.33MnO3 thin films

We report about La0.67Sr0.33MnO3 single crystal manganite thin films in interaction with a gold capping layer. With respect to uncoated manganite layers of the same thickness, Au-capped 4 nm-thick manganite films reveal a dramatic reduction (about 185 K) of the Curie temperature TC and a lower saturation low-temperature magnetization M0. A sizeable TC reduction (about 60 K) is observed even when an inert SrTiO3 layer is inserted between the gold film and the 4 nm-thick manganite layer, suggesting that this effect might have an electrostatic origin