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Shangxiong Huangfu, Zurab Guguchia, Denis Cheptiakov, Xiaofu Zhang, H. Luetkens, Dariusz Jakub Gawryluk, Tian Shang, Fabian O. von Rohr, A. Schilling
Abstract
The nickelate $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{8}$ features quasi-two-dimensional layers consisting of three stacked square-planar $\mathrm{Ni}{\mathrm{O}}_{2}$ planes, in a similar way to the well-known cuprate superconductors. The mixed-valent nature of Ni and its metallic properties makes it a candidate for potentially unconventional superconductivity. We have synthesized $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{8}$ by topotactic reduction of $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{10}$ in 10% hydrogen gas, and report on measurements of powder-neutron diffraction, magnetization, and muon-spin rotation (\textmu{}SR). We find that $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{8}$ shows complicated spin-glass behavior with a distinct magnetic memory effect in the temperature range from 2 to 300 K and a freezing temperature ${T}_{s}\ensuremath{\approx}68\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. Moreover, the analysis of \textmu{}SR spectra indicates two magnetic processes characterized by remarkably different relaxation rates: a slowly relaxing signal, resulting from paramagnetic fluctuations of Pr/Ni ions, and a fast-relaxing signal, whose relaxation rate increases substantially below $\ensuremath{\approx}70\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ which can be ascribed to the presence of short-range correlated regions. We conclude that the complex spin-freezing process in $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{8}$ is governed by these multiple magnetic interactions. It is possible that the complex magnetism in $\mathrm{P}{\mathrm{r}}_{4}\mathrm{N}{\mathrm{i}}_{3}{\mathrm{O}}_{8}$ is detrimental to the occurrence of superconductivity.