Dimensionality of vortex matter in superconducting infinite-layer nickelates

TL;DR

This study investigates the dimensionality of superconductivity in infinite-layer nickelates by analyzing vortex phase diagrams, revealing that disorder influences the transition from quasi-2D to pure 2D states, highlighting disorder as a key control parameter.

Contribution

It introduces a vortex phase diagram approach to determine superconducting dimensionality and shows disorder induces a crossover to pure 2D behavior in nickelates.

Findings

Superconducting nickelates exhibit a vortex liquid-to-glass transition of quasi-2D nature.

Increasing disorder causes a crossover into a pure 2D state.

Disorder acts as a key control parameter, affecting the decoupling of NiO2 planes.

Abstract

Characterizing the dimensionality of the superconducting state in infinite-layer (IL) nickelates is essential for understanding its nature. Most studies have addressed this by examining the anisotropy of the upper critical fields. However, the dominance of Pauli paramagnetic effects over orbital effects complicates the interpretation of these experiments in terms of dimensionality. Here, we approach the question from a different perspective by mapping the vortex phase diagram. We show that superconducting Pr0.8Sr0.2NiO2 thin films with low disorder exhibit a vortex liquid-to-glass transition of a quasi-two-dimensional (2D) nature. In contrast, increasing disorder drives a crossover into a pure 2D state. This demonstrates that pure bidimensionality is an extrinsic property, resulting from the decoupling of NiO2 planes due to enhanced disorder. Our findings establish disorder as a key control parameter of superconductivity in IL nickelates and suggest that it resides within the NiO2 planes, providing two fundamental insights for understanding these materials.