Overlooked Transportation Anisotropies in d-Band Correlated Rare-Earth Perovskite Nickelates

Anisotropies in electronic transportations conventionally originate from the nature of low symmetries in crystal structures and were not anticipated for perovskite oxides with crystal asymmetries much smaller than, e.g., van der Waals or topological crystal. Beyond conventional expectations, here we demonstrate pronounced anisotropies in the inter-band Coulomb repulsion-dominated electronic transportation behaviors in the low-dimensional perovskite family of rare-earth nickelates (ReNiO₃). The in-plane orbital entropy associated to the in-plane symmetry of the NiO₆ octahedron within ReNiO₃ causes intrinsic anisotropies for the gradual orbital transition with temperature to regulate their thermistor transportations. Extrinsically imparting biaxial interfacial strains amplifies the anisotropies in the electronic transportation of ReNiO₃. It unveils the overlooked role of orbital directionalities within low-dimensional correlated perovskites that triggers anisotropic transportations despite their higher crystal symmetries, and this introduces new freedoms to regulate their correlated transportations.