Low-Temperature Anomalous Spin Correlations And Kondo Effect In Ferromagnetic Srruo3/Lanio3/La0.7sr0.3mno3 Trilayers

A systematic comparative study of the electronic transport and ferromagnetic resonance of ultrathin trilayers (TLs) of SrRuO3/LaNiO3/La0.7Sr0.3MnO3 on (001)- and (111)-oriented SrTiO3 (STO) substrates has been reported. An unusual upturn in resistivity rho(T) at low temperature (so called Kondo-like behavior) accompanied by the negative magnetoresistance has been observed. For temperatures larger than the Kondo temperature (T-K), rho(T) is in good agreement with the Hamann's impurity resistivity model rho(T > T-K) proportional to (ln(T/T-K))(-2) for spin S = 1/2 and 3/2 for the TLs on (001)-STO and (111)-STO, respectively. At the temperatures T >> T-K, electron-electron [rho(T) proportional to T-2] contribution dominates over those appearing due to the electron-phonon interaction [rho(T) proportional to T-5] and 2-Magnon scattering. Using the ferromagnetic resonance near the Curie temperature of La0.7Sr0.3MnO3, we evaluated the contribution of surface anisotropies (K-s) as well as in-plane volume anisotropies (K-nu) : K-s similar to -9.57 x 10(-4) (-6.68 x 10(-4)) J/m(2) and K-nu similar to 4.04 x 10(5) (3.31 x 10(5)) J/m(3) for the TLs on (001)-STO (TLs on (111)-STO). In addition, the Gilbert damping constant is determined which varies between 0.32 (0.23) and 0.16 (0.19) having spin mixing conductance, g(up arrow)down arrow = 5.2 x 10(19) (13.38 x 10(19)) m(-2) for TLs on (001)-STO ((111)-STO).