Low-temperature anomalous spin correlations and Kondo effect in ferromagnetic SrRuO3/LaNiO3/La0.7Sr0.3MnO3 trilayers

Abstract

A systematic comparative study of the electronic transport and ferromagnetic resonance of ultrathin trilayers (TLs) of ${\mathrm{SrRuO}}_{3}/{\mathrm{LaNiO}}_{3}/{\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ on (001)- and (111)-oriented ${\mathrm{SrTiO}}_{3}$ (STO) substrates has been reported. An unusual upturn in resistivity $\ensuremath{\rho}(T$) at low temperature (so called Kondo-like behavior) accompanied by the negative magnetoresistance has been observed. For temperatures larger than the Kondo temperature $({T}_{\text{K}})$, $\ensuremath{\rho}(T$) is in good agreement with the Hamann's impurity resistivity model $\ensuremath{\rho}(Tg{T}_{\text{K}})\ensuremath{\propto}{(ln(T/{T}_{\text{K}}))}^{\ensuremath{-}2}$ for spin $S=1/2$ and 3/2 for the TLs on (001)-STO and (111)-STO, respectively. At the temperatures $T\ensuremath{\gg}{T}_{\text{K}}$, electron-electron $[\ensuremath{\rho}(T)\ensuremath{\propto}{T}^{2}]$ contribution dominates over those appearing due to the electron-phonon interaction $[\ensuremath{\rho}(T)\ensuremath{\propto}{T}^{5}]$ and 2-Magnon scattering. Using the ferromagnetic resonance near the Curie temperature of ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$, we evaluated the contribution of surface anisotropies $({K}_{\text{s}})$ as well as in-plane volume anisotropies $({K}_{\ensuremath{\nu}})$ : ${K}_{\text{s}}\ensuremath{\sim}\ensuremath{-}9.57\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ($\ensuremath{-}6.68\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$) ${\mathrm{J}/\mathrm{m}}^{2}$ and ${K}_{\ensuremath{\nu}}\ensuremath{\sim}4.04\ifmmode\times\else\texttimes\fi{}{10}^{5}\phantom{\rule{0.16em}{0ex}}(3.31\ifmmode\times\else\texttimes\fi{}{10}^{5}$) ${\mathrm{J}/\mathrm{m}}^{3}$ 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, ${\mathrm{g}}^{\ensuremath{\uparrow}\ensuremath{\downarrow}}=\phantom{\rule{4pt}{0ex}}5.2\ifmmode\times\else\texttimes\fi{}{10}^{19}$ ($13.38\ifmmode\times\else\texttimes\fi{}{10}^{19}$) ${\mathrm{m}}^{\ensuremath{-}2}$ for TLs on (001)-STO ((111)-STO).