Electronic structure and anisotropic magnetotransport in the topological kagome ferromagnet MgMn6Sn6

Abstract

We report the magnetic, magnetotransport, and electronic properties of the kagome ferromag net MgMn6Sn6 using magnetization, angle dependent magnetoresistance, x-ray magnetic circular dichroism (XMCD), angle resolved photoemission spectroscopy (ARPES), and first-principles cal culations. MgMn6Sn6 exhibits ferromagnetic ordering near TC=295 K with pronounced easy plane magnetic anisotropy. At low temperatures and low magnetic fields, the magnetoresistance (MR) is strongly anisotropic with respect to the magnetic field orientation, evolving from a predominantly negative MR for in-plane fields to a more quadratic behavior for out-of-plane fields. Angle depen dent measurements further reveal a pronounced twofold MR anisotropy with additional higher order contributions. The finite orbital-to-spin moment ratio revealed by XMCD suggests a significant role of spin-orbit coupling (SOC) in MgMn6Sn6. The first-principles calculations show a Dirac-like band crossing at the K point and a van Hove singularity (VHS) at the M point, as expected for kagome materials. ARPES measurements resolve a sixfold symmetric Fermi surface and its systematic evo lution with binding energy, in overall agreement with first-principles calculations. The measured band dispersions are also broadly consistent with the calculated multiband electronic structure. These results establish the connection between magnetic anisotropy, anisotropic magnetotransport, and the kagome derived electronic structure of MgMn6Sn6.