Paramagnetically driven superconducting re-entrance in Eu-doped infinite layer nickelates

TL;DR

This paper investigates how magnetic Eu ions influence superconductivity in Eu-doped NdNiO2, revealing field-induced re-entrant superconductivity driven by magnetic polarization effects, advancing understanding of magnetic interactions in nickelate superconductors.

Contribution

It uncovers the role of magnetic Eu ions in inducing re-entrant superconductivity in Eu-doped NdNiO2, highlighting the interplay between magnetic polarization and superconductivity.

Findings

Field-induced re-entrant superconductivity observed in Eu-doped NdNiO2.

Magneto-transport effects are influenced by Eu2+ and Nd3+ ion polarization.

Analysis of Hall effect and critical fields elucidates magnetic contributions to superconductivity.

Abstract

The breakthrough discovery of superconductivity in infinite-layer nickelates, and subsequently in several superconducting nickelates with more complex layered structures, capped a search spanning more than two decades and opened an entirely new field of research. Significant efforts aim to increase the critical temperature, to determine the electronic structure of the system, the underlying pairing mechanism, and the similarities between this system and cuprates - Ni1+ in infinite-layer nickelates being isoelectronic to Cu2+ in high-Tc cuprates. Here, we explore the unique role of magnetic rare earth ions in superconducting Eu-doped NdNiO2. We show that the field-induced re-entrant superconductivity which we evidence in this compound is the result of a delicate balance between the competing effects of the Eu2+ and Nd3+ ions. Our analyses of the extraordinary Hall effect and modeling of the superconducting critical fields demonstrate that the influence of these ions on magneto-transport is only felt when they are polarized by a magnetic field.