Anisotropic optical and magneto-optical properties of antiferromagnetic Weyl semimetal Mn3Sn epitaxial thin films

Antiferromagnetic Weyl semimetal Mn3Sn exhibiting strong magneto-optical Kerr effect (MOKE) due to non-zero Berry curvature is attractive for spintronic and photonic device applications. Despite many reports on the anisotropic anomalous Hall effect (AHE), so far, there have been few studies on its anisotropic optical properties. In this work, we experimentally characterized the anisotropic optical and magneto-optical (MO) properties of Mn3Sn(20)/MgO(110) and Mn3Sn(0001)/Al2O3(0001) epitaxial films using ellipsometry in the wavelength range from 300 to 1690 nm. By measuring the Mueller matrix of magnetized Mn3Sn, the anisotropic permittivity tensor is determined using the 4 × 4 transfer matrix method. Temperature dependent MOKE measurement confirmed the origin of the anisotropic MO effect to the non-zero Berry curvature of the chiral magnetic phase. The measured permittivity also agrees well with first-principles calculations. The anisotropic optical and MO properties determined in this work can be useful for Mn3Sn based spintronic device characterization and photonic device development.