Density-wave phases, anisotropic transport, and Planckian dissipation in single crystals of the superconductor La3Ni2O7

Abstract

Pressure-induced superconductivity in bilayer nickelates provides a platform for investigating intertwined roles of charge/spin orders and electric transport in unconventional superconductivity. However, important quantitative information on the transport, such as the absolute value of the resistivity, the anisotropy, and the scattering rate of carriers, remains insufficient due to the lack of accurate measurements using large single crystals. Here we establish a high-precision pressure-temperature phase diagram of high-quality La3Ni2O7 single crystals, by measuring the in-plane and out-of-plane resistivities. We resolve two distinct anomalies associated with density-wave formation with contrasting pressure dependences. The pressure-induced structural transition enhances not only the resistivity values for both directions, but also its anisotropy at low temperatures, demonstrating a pronounced effect of density-wave order on the charge dynamics. Superconductivity with zero-resistance emerges near the boundary where the density-wave phases are fully suppressed, and above Tc, the resistivity exhibits a temperature-linear dependence over a wide temperature range while the scattering rate falls within a regime of the Planckian limit. Our results show that pressure dramatically changes the anisotropic charge transport via modifying density-wave orders, and eventually produces a pronounced strange-metal state with strong scatterings, from which superconductivity develops. This establishes robust density-wave correlations and Planckian dissipation as remarkable features of La3Ni2O7.