Spin-glass state in nickelate superconductors

TL;DR

This paper reports the discovery of spin-glass behavior in nickelate superconductors at temperatures much higher than their superconducting transition, contrasting with cuprates, and highlights substrate-dependent effects on magneto-optical properties.

Contribution

It reveals the presence of spin-glass states in nickelate superconductors and demonstrates substrate-dependent variations in magneto-optical effects, providing new insights into their magnetic properties.

Findings

Spin-glass behavior observed at high temperatures.

Substrate significantly affects Kerr effect magnitude and onset.

Superconducting temperature remains unaffected by substrate changes.

Abstract

Magneto-optical measurements in La${}_{0.8}$Sr${}_{0.2}$NiO${}_2$ and Nd${}_{0.825}$Sr${}_{0.175}$NiO${}_2$ reveal an intriguing new facet of infinite-layer nickelate superconductors: the onset of spin-glass behavior at a temperature far exceeding the superconducting critical temperature $T_c$. This discovery sharply contrasts with copper oxide superconductors, where magnetism and superconductivity remain largely exclusive. Moreover, the magnitude and onset temperature of the polar Kerr effect in Nd${}_{0.825}$Sr${}_{0.175}$NiO${}_2$ fabricated on SrTiO${}_3$ and (LaAlO${}_3$)${}_{0.3}$(Sr${}_2$TaAlO${}_6$)${}_{0.7}$ substrates differ dramatically, while $T_c$ does not.