Evolution of the metallic state of LaNiO$_3$/LaAlO$_3$ superlattices measured by $^8$Li $β$-detected NMR

Abstract

Using ion-implanted 8 Li 𝛽-detected NMR, we study the evolution of the correlated metallic state of LaNiO 3 in a series of LaNiO 3 /LaAlO 3 superlattices as a function of bilayer thickness. Spin-lattice relaxation measurements in an applied field of 6.55 T reveal two equal amplitude components: one with metallic (𝑇-linear) 1/𝑇 1 , and a second with a more complex 𝑇-dependence. The metallic character of the slow relaxing component is only weakly affected by the LaNiO 3 thickness, while the fast component is much more sensitive, exhibiting the opposite temperature dependence (increasing towards low 𝑇) in the thinnest, most magnetic samples. The origin of this bipartite relaxation is discussed.