Weakly Anisotropic Superconductivity of Pr4Ni3O10 Single Crystals.

Since the discovery of high-temperature superconductivity, studying the upper critical field and its anisotropy has been crucial for understanding the superconducting mechanism and guiding applications. Here, we perform in situ high-pressure angular-dependent electrical transport measurements on Pr4Ni3O10 single crystals using a custom diamond anvil cell (DAC) rotator, confirming its anisotropic superconductivity. The anisotropy parameter γ, derived from the upper critical fields (μ0Hc2) for H⊥ab and H//ab, is approximately 1.6, decreasing with increasing temperature and approaching 1 near Tc. Comparing effective mass anisotropy and interblock distance in cuprates and iron-based superconductors (FeSCs) reveals that Pr4Ni3O10 single-crystal superconductors are consistent with a two-band model, where intralayer quantum confinement within the unit cell induces interlayer coherence, thereby leading to three-dimensional (3D) superconductivity. This study not only establishes the existence of weakly anisotropic superconductivity in bulk Ruddlesden-Popper nickelates but also provides critical insight into the role of dimensionality in high-temperature superconductivity.