Giant Anomalous and Topological Hall Conductivity in a Ge substituted HoMn6Sn6 single crystal

Authors: Jemma DeFeo, Venkateswara Yenugonda

SUNY Campus: Buffalo State

Presentation Type: Poster

Location: Old Union Hall

Presentation #: 39

Timeslot: Session D 3:00-4:00 PM

Abstract: Kagome systems are 2D materials with corner shared triangles in the hexagonal symmetry and they attained renewed in the field of topological materials due to discovery of flat electronic bands arising due to destructive interference, Van Hove singularities, Dirac cones, spin-orbit coupled driven topology, unconventional charge-density waves, magnetically intertwined superconductivity. In this letter, we are reporting the synthesis, characterization of magnetic, resistivity and Hall measurements along with the first principles simulations supporting the findings in HoMn6Sn4Ge2 single crystals. The system exhibits two ferrimagnetic transitions at TC1 ∼ 108 K and TC2 ∼ 380 K respectively. Distinct magnetic behavior along the ab-plane and c-direction confirm magnetocrystalline anisotropy. The system undergoes a change in easy magnetization axis from c−direction to ab-plane above TC1. Resistivity measurements show the metallic nature. A giant anomalous Hall conductivity −σyz ∼ 2800 Ω−1 cm−1 was observed at around 125 K, which is highest so far in R166 alloys (more than 7 times higher than the previously reported highest value in LiMn6Sn6). The topological Hall exhibits two dips and one peak in the temperature region II. Interestingly the observed topological Hall resistivity value exceeds the previously reported giant topological Hall effect in YMn6Sn6. Ab-initio calculations by Fleur DFT code predicts the ferrimagnetic ground state with spin moments of -4.22, 2.19 µB and orbitals moments of -4.93, 0.02 µB on Ho and Mn ions, which are in good agreement with the earlier neutron diffraction studies.