Special Condensed Matter Seminar | Yan Sun, Max Planck | "Linear response in topological semimetals" | Jadwin 303

Mon, May 14, 2018, 1:15 pm
Jadwin 303

Abstract:  We have found that the strong spin Hall effect in TaAs is mainly dominated from the Weyl points and nodal-line-like Fermi surface, which implying a strong interplay between the topological band structure and Berry curvature in topological semimetals. With this guiding principle, we have successfully understood the strong spin Hall effect in IrO2 and found the nodal line band structures in it. Generalizing this principle to time reversal symmetry breaking system, we have predicted strong anomalous Hall effect in magnetic Weyl semimetal Co3Sn2S2, which was verified by our experimental collaborators.  Owing to the low charge carrier density and large Berry curvature from the nodal line band structure, the anomalous Hall conductivity and anomalous Hall angle experimentally reach up to 1130 S/cm and 20% respectively. Further, the anomalous Hall effect can even exist with zero net moments in the absence of the symmetry operation that changes the sign of Berry curvature. And the anomalous Hall effect can be strongly enhanced by the special band structures of Weyl points and nodal lines. Following this guiding direction, we have predicted a strong anomalous Hall effect in the compensated ferrimagnetic Weyl semimetal Ti2MnAl and noncollinear antiferromagnetic Weyl metal Mn3Ge with vanishing net magnetic moments. Our work is helpful for the comprehensive understanding of the linear response effect in topological materials and their future applications.