Spin-glass state in nickelate superconductors

Magneto-optical measurements in La_0.8Sr_0.2NiO₂ and Nd_0.825Sr_0.175NiO₂ 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_0.825Sr_0.175NiO₂ fabricated on SrTiO₃ and (LaAlO₃)_0.3(Sr₂TaAlO₆)_0.7 substrates differ dramatically, while \(T_c\) does not.