Correlated Hund's Metallic Phase in Kagome Nodal Surface Semimetal: Sc₃Mn₃Al₇Si₅

Correlated nodal surface semimetal phase, which emerges in three dimensional topological materials has garnered accrued interest recently. Differing from well-known nodal semimetals, surface semimetal phase appears in the special nodal plane of Brillouin zone, protected by either space-time inversion and sublattice symmetries or nonsymmorphic two-fold screw rotation and time-reversal symmetries. Here, we theoretically study a new Mn-based Kagome metal Sc₃Mn₃Al₇Si₅ (SMAS) using combined density functional and dynamical mean-field theory methods. An extensive symmetry analysis of electronic band structure reveals that SMAS hosts a nonsymmorphic nodal surface at <i>k_z</i>=π plane, guaranteed by a product of two-fold screw rotation and time-reversal symmetry. The doubly degenerate nodal surface band is robust against spin-orbit coupling and exists ubiquitously at every <i>k</i>-point on the nodal plane. Further, dynamical mean-field calculation shows that SMAS features Hund's metallic phase, where Hund's coupling drives a transition from a Fermi-liquid with small local spin moment to a non-Fermi-liquid with large fluctuating spin moment. The calculated DC resistivity suggests that SMAS is predominantly metallic.