Hund's metallicity in $3d$ transition metal oxides constitutes a rare class of compounds, since they have been long understood considering the dominance of Hubbard $U$. ${\mathrm{LiV}}_2{\mathrm{O}}_4\text{and} {\mathrm{Sr}}_2{\mathrm{CoO}}_4$ belong to this rare class of metals; among them, ${\mathrm{LiV}}_2{\mathrm{O}}_4$ has been the subject of extensive investigations for its unconventional heavy-fermion behavior, while studies on ${\mathrm{Sr}}_2{\mathrm{CoO}}_4$ remain limited despite its anomalous ferromagnetic ground state. In this study, we report an unusual spin-orbital selective localization in ${\mathrm{Sr}}_2{\mathrm{CoO}}_4$ consistent with a Kondo-like resonance at $\sim 70\mathrm{K}$ in the spin-$up$ channel of orbitals of $t_{2g}$ symmetry using a combination of Density functional theory and Dynamical mean-field theory calculations. Correspondingly, an appreciable reduction in the magnetization below $T=100\mathrm{K}$ is further suggestive of a partial Kondo-like screening of local moments active at low temperatures, providing a plausible explanation for its effective spin magnetization state and upturn in its resistivity observed in experimental reports. We note a significant effect of Hund's induced spin-orbital selective incoherence in dictating the temperature evolution of its macroscopic observables e.g., spin-spin correlation function and effective local moment. Our results reveal a potentially distinct/new form of spin-dependent selectivity induced via Hund's coupling in addition to the conventional orbital-selectivity in the Hund's metals, as a plausible key mechanism in stabilizing their long-range magnetic order.

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• Electronic structure
• Magnetic order
• Strongly correlated systems
• Transition metal oxides
• DFT+DMFT