Spin-glass state in nickelate superconductors

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.