Spin-glass behavior, spin-fluctuations and superconductivity in Sr2Y(Ru1-uCuu)O6

[[abstract]]Muon spin rotation measurements of Sr2Y(Ru1-uCuu)O6 (for u=0.1) reveal two distinct muon sites: one located in a SrO layer (which is superconducting at low temperatures) and the other in a Y(Ru1-uCuu)O4 layer (which is magnetically ordered at low temperatures). A precursor spin-glass state due to the Ru moments is detected in high fields (≈3.3 kOe) in Y(Ru1-uCuu)O4 layers, with a spin-glass temperature of TG=29.25K. The Y(Ru1-uCuu)O4 layers order ferromagnetically in the a-b planes at the Néel temperature, TN≈23K. This in-plane ferromagnetism alternates direction between adjacent Y(Ru1-uCuu)O4 planes, resulting in a net antiferromagnetic structure. Although the onset of superconductivity is observed both by electron spin resonance and by dc susceptibility to occur for temperatures up to about Tc,onset≈49K, this superconductivity is adversely affected by the Ru moments that fluctuate for T>TN producing magnetic fields that break pairs in the SrO layers. The muons, as well as other probes, sense the more-robust static superconductivity for TTN are frozen in-plane. Hence strictly speaking, the superconducting transition temperature is the same as TN, which is far below Tc,onset. Below TN there are no pair breaking fluctuating magnetic fields in the SrO layers where the hole condensate resides.[[incitationindex]]SCI[[booktype]]紙

Analysis of electrical resistance data from Snider et al., Nature 586‾\underline{586}, 373 (2020)

Digital data for the temperature dependence of electrical resistance, which were extracted and analyzed by Hamlin (arXiv:2210.10766v1) from the pdf file published for "Room temperature superconductivity in a carbonaceous sulfur hydride," show asymmetric serrations in data for 267 GPa in zero magnetic field that comprise smooth and digitized parts. Further analysis shows that the smooth part exhibits a step at the transition of ~16% in magnitude relative to the data. Notably, there is no evidence of asymmetric serrations in extracted data for lower pressures (184-258 GPa) or for 267 GPa in an applied magnetic field (1-9 T). Several questions are raised, the answers to which would help toward resolving these outstanding issues.Comment: 6 pages; 10 figure