Fermi-liquid transport beyond the upper critical field in superconducting La${}_2$PrNi${}_2$O${}_7$ thin films

Abstract

Unconventional superconductivity typically emerges out of a strongly correlated normal state, manifesting as a highly renormalized Fermi liquid or a strange metal with $T$-linear resistivity. In Ruddlesden-Popper bilayer nickelates, superconductivity with a critical temperature $T_{\mathrm{c}}$ exceeding 80 and 40~K has been respectively realised in pressurized bulk crystals and epitaxially strained thin films. These advancements call for the characterisation of fundamental normal-state and superconducting parameters in these new materials platforms of high-$T_{\mathrm{c}}$ superconductivity. Here we report detailed magnetotransport experiments on superconducting La${}_2$PrNi${}_2$O${}_7$ (LPNO) thin films under pulsed magnetic fields up to 64~T and access the normal-state behaviour over a wide temperature range between 1.5 and 300~K. We find that the normal state of thin-film LPNO exhibits the hallmarks of Fermi-liquid transport, including $T^2$ temperature dependence of resistivity and Hall angle, and $H^2$ magnetoresistance obeying Kohler scaling. Using the empirical Kadowaki-Woods ratio, we estimate a quasiparticle effective mass $m^{\ast }/m_e\simeq 10$, thereby revealing the highly renormalized Fermi liquid state therein. Our results demonstrate that thin-film LPNO follows the same $T_{\mathrm{c}}/T_{\mathrm{F}}$ scaling observed across a myriad of strongly correlated superconductors and establish key normal-state characteristics of strained bilayer superconducting nickelates.

Cited by in corpus (2)

• Impact of multiband effects on non-Fermi-liquid transport phenomena in bilayer nickelates
• Bridging ambient- and high-pressure superconductivity in La${}_2$LnNi${}_2$O${}_7$ films