Spin structure and dynamics of the topological semimetal Co3Sn2-xInxS2

Abstract

The anomalous Hall effect (AHE), typically observed in ferromagnetic (FM) metals with broken time-reversal symmetry, depends on electronic and magnetic properties. In Co3Sn2-xInxS2, a giant AHE has been attributed to Berry curvature associated with the FM Weyl semimetal phase, yet recent studies report complicated magnetism. We use neutron scattering to determine the spin dynamics and structures as a function of x and provide a microscopic understanding of the AHE and magnetism interplay. Spin gap and stiffness indicate a contribution from Weyl fermions consistent with the AHE. The magnetic structure evolves from c-axis ferromagnetism at $$x = 0$$ x = 0 to a canted antiferromagnetic (AFM) structure with reduced c-axis moment and in-plane AFM order at $$x = 0.12$$ x = 0.12 and further reduced c-axis FM moment at $$x = 0.3$$ x = 0.3 . Since noncollinear spins can induce non-zero Berry curvature in real space acting as a fictitious magnetic field, our results revealed another AHE contribution, establishing the impact of magnetism on transport.

Half-Metallic Ferromagnetism in Radical-Bridged Metal–Organic Frameworks

“…In a kagome lattice, there can exist a canted AFM state. − Therefore, we also considered two in-plane 120° spin configurations, as depicted in Figure c. The DFT + U calculated band structures and spin densities of the two AFM-120 configurations obtained after geometry optimizations are provided in the SI (Figures S18–S23).…”

How to Enhance Anomalous Hall Effects in Magnetic Weyl Semimetal Co3Sn2S2?

“…Since the atomic numbers of Sn ( Z = 50) and In ( Z = 49) are nearly the same, for small x , there is no significant change in SOC, and In doping is expected to only shift the Fermi energy. Interestingly, the peak of AHC is also followed by a change in the magnetic structure from a simple ferromagnet along the c axis ( x = 0) to a canted AFM with a reduced c axis moment ( x = 0.12) . A direct correlation of this change in the magnetic structure with the evolution of AHC is not yet known.…”

“…In Co 3 Sn 2−x In x S 2 , the maximum of AHC coincides with the establishment of coexisting c-axis ferromagnetic and in-plane antiferromagnetic order. 23,24 AHE is suppressed 25 in thinner films (<20 nm) of lower quality 11,26 , while it is enhanced in nanoflakes 27 with high mobility. 9 The exploitation of valley degrees of freedom is emerging as an avenue for the anomalous valley Hall effect.…”

“…Interestingly, the peak of AHC is also followed by a change in the magnetic structure from a simple ferromagnet along the c axis (x = 0) to a canted AFM with a reduced c axis moment (x = 0.12). 23 A direct correlation of this change in the magnetic structure with the evolution of AHC is not yet known. Further, the doped In atoms in Co 3 Sn 2 S 2 can form spin down polarized localized bound states 77 , and the possible role of these bound states on altering bulk properties has not yet been probed.…”