Fermi-liquid transport beyond the upper critical field in superconducting LaPrNiO thin films

Unconventional superconductivity typically emerges out of a strongly correlated normal state, manifesting as a Fermi liquid with highly enhanced effective mass or a strange metal with  -linear resistivity in the zero-temperature limit. In Ruddlesden-Popper bilayer nickelates  Ni O , superconductivity with a critical temperature ( ) exceeding 80 and 40 K has been respectively realised in bulk crystals under high pressure and thin films under compressive strain. These advancements create new materials platforms to study the nature of high-  superconductivity, calling for the characterisation of fundamental normal-state and superconducting parameters therein. Here we report detailed magnetotransport experiments on superconducting La PrNi O  (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 LPNO exhibits the hallmarks of Fermi liquid transport, including   temperature dependence of resistivity and Hall angle, and   magnetoresistance obeying Kohler scaling. Using the empirical Kadowaki-Woods ratio relating the transport coefficient and electronic specific heat, we estimate a quasiparticle effective mass   in PLNO, thereby revealing the highly renormalized Fermi liquid state which hosts the high-temperature nickelate superconductivity. Our results demonstrate that LPNO follows the same   scaling observed across a wide variety of strongly correlated superconductors and provide crucial constraints for a viable model for superconductivity in bilayer nickelates.

Read the whole article by Hsu et al. on arXiv.