Large upper critical fields and dimensionality crossover of superconductivity in the infinite-layer nickelate La0.8Sr0.2NiO2

The recent discovery of superconductivity in nickelates, sharing structural and electronic similarities with cuprates, is crucial for understanding the high-${T}_{c}$ superconducting pairing mechanism. Here, the authors study the ${H}_{c2}$ of a high-quality La${}_{0.8}$Sr${}_{0.2}$NiO${}_{2}$ thin film. Significantly large ${H}_{c2}$ ($\ensuremath{\sim}$ 40 T for $H$ || $c$ and $\ensuremath{\sim}$ 52 T for $H$ || $a\phantom{\rule{0}{0ex}}b$) are obtained. The anisotropy decreases from $\ensuremath{\sim}$10 near ${T}_{c}$ to $\ensuremath{\sim}$1.5 at 2 K, which confirms a crossover from 2D to 3D superconductivity based on the angle dependence of ${H}_{c2}$.