Tuning the electronic band structure in a kagome ferromagnetic metal via magnetization

Abstract

Materials with zero energy band gap display intriguing properties including high sensitivity of the electronic band structure to external stimulus such as pressure or magnetic field. An interesting candidate for zero energy band gap is Weyl nodes at the Fermi level ${E}_{\mathrm{F}}$. A prerequisite for the existence of Weyl nodes is to either have inversion or time reversal symmetry broken. Weyl nodes in systems with broken time reversal symmetry are ideal to realize the tunability of the electronic band structure by magnetic field. Theoretically, it has been shown that in ferromagnetic Weyl materials, the band structure is dependent upon the magnetization direction and thus the electronic bands can be tuned by controlling the magnetization direction. Here we demonstrate, by analysis of the Hall resistivity, tuning of the band structure in a kagome Weyl ferromagnetic metal ${\mathrm{Fe}}_{3}{\mathrm{Sn}}_{2}$ with magnetization and magnetic field. Owing to spin-orbit coupling, we observe changes in the band structure depending on the magnetization direction that amount to a decrease in the net carrier density by a factor of 4 when the magnetization lies in the kagome plane as compared to when the magnetization is along the $c$ axis. Our discovery opens the way for tuning the carrier density in ferromagnetic materials.