New angle on cosmic rays

Topological Hall Effect Anisotropy in Kagome Bilayer Metal Fe_{3}Sn_{2}

Kagome lattice materials have attracted growing interest for their topological properties and flatbands in electronic structure. We present a comprehensive study on the anisotropy and out-of-plane electric transport in Fe_{3}Sn_{2}, a metal with bilayer of Fe kagome planes and with massive Dirac fermions that features high-temperature noncollinear magnetic structure and magnetic skyrmions. For the electrical current path along the c axis, in micron-size crystals, we found a large topological Hall effect over a wide temperature range down to spin-glass state. Twofold and fourfold angular magnetoresistance are observed for different magnetic phases, reflecting the competition of magnetic interactions and magnetic anisotropy in kagome lattice that preserve robust topological Hall effect for inter-kagome bilayer currents. This provides new insight into the anisotropy in Fe_{3}Sn_{2}, of interest in skyrmionic-bubble application-related micron-size devices.

Giant Thermoelectric Power Factor Anisotropy in PtSb1.4Sn0.6

We report on the giant anisotropy found in the thermoelectric power factor (S²σ) of marcasite structure-type PtSb_1.4Sn_0.6 single crystal. PtSb_1.4Sn_0.6, synthesized using an ambient pressure flux growth method upon mixing Sb and Sn on the same atomic site, is a new phase different from both PtSb₂ and PtSn₂, which crystallize in the cubic Pa3̅ pyrite and Fm3̅m fluorite unit cell symmetry, respectively. The large difference in S²σ for heat flow applied along different principal directions of the orthorhombic unit cell stems mostly from anisotropic Seebeck coefficients.