Possible Sources of Trigger Mechanism of Electron-phonon Interactions in Doped CuTl-1223 Superconductors

This article underlines the important role of copper Cu(3d9) spins at the CuO2 planer sites to comprehend the physics of High temperature Superconductivity . In such studies we have reported the characterization results of samples (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ , (Cu0.5Tl0.5)(BaCa)(CaMg)Cu1Zn2O10-δ , (Cu0.5Tl0.5)(BaCa)(CaMg) Zn3O10-δ and (AyTl1-y)(BaCa)(CaMg) Zn3O10-δ (A=Ag, K, Ni, Mn; y=0,0.5). Samples were prepared at normal pressure by using two-steps solid state reaction method. The characterization of samples is done via x-ray diffraction (XRD), resistivity (RT) and Fourier Transform Infrared (FTIR) absorption measurements. Intrinsic superconducting parameters and activation energy of all sample is estimated applying two theoretical models, Fluctuation Induced conductivity (FIC) analysis and Mott 3D-VRH. The XRD and FTIR absorption measurements have confirmed the intrinsic doping of K, Ag, Ni, Mn and Zn. Interestingly, samples (Cu0.5Tl0.5)(BaCa)(CaMg) Zn3O10-δ without CuO2 planes have exhibited superconducting behavior above 77K. To verify the role of Cu(3d9) atoms in superconductivity we have synthesized (AyTl1-y)(BaCa)(CaMg) Zn3O10-δ (A=Ag, K, Mn, Ni; y=0,0.5) samples. In aforementioned samples, doping of Ni, Mn, K, Ag ions in Cu1-xTlxBa2O4-δ charge reservoir layer instead of Cu-atoms destroys the superconductivity completely and leads to semiconducting behavior. Key objective to preparing these samples is to investigate the role of two major parameters local moments (spin) of copper atoms and net carrier’s concentration in superconductivity.

Lattice-shifted nematic quantum critical point in FeSe1−xSx

We report the evolution of nematic fluctuations in FeSe1−xSx single crystals as a function of Sulfur content x across the nematic quantum critical point (QCP) xc ~ 0.17 via Raman scattering. The Raman spectra in the B1g nematic channel consist of two components, but only the low energy one displays clear fingerprints of critical behavior and is attributed to itinerant carriers. Curie–Weiss analysis of the associated nematic susceptibility indicates a substantial effect of nemato-elastic coupling, which shifts the location of the nematic QCP. We argue that this lattice-induced shift likely explains the absence of any enhancement of the superconducting transition temperature at the QCP. The presence of two components in the nematic fluctuations spectrum is attributed to the dual aspect of electronic degrees of freedom in Hund’s metals, with both itinerant carriers and local moments contributing to the nematic susceptibility.