Abstract

Abstract By using muon spin relaxation ( μ SR) measurements, we perform a comparative study of the microscopic magnetism in the parent compounds of infinite-layer nickelate superconductors R NiO 2 ( R = La, Nd). In either compound, the zero-field μ SR spectra down to the lowest measured temperature reveal no long-range magnetic order. In LaNiO 2 , short-range spin correlations appear below T = 150 K, and spins fully freeze below T ~ 10 K. NdNiO 2 exhibits a more complex spin dynamics driven by the Nd 4 f and Ni 3 d electron spin fluctuations. Further, it shows features suggesting the proximitiy to a spin-glass state occuring below T = 5 K. In both compounds, the spin behavior with temperature is further confirmed by longitudinal-field μ SR measurements. These results provide new insight into the magnetism of the parent compounds of the superconducting nickelates, crucial to understanding the microscopic origin of their superconductivity.