Magnetic Structure and Weak Ferromagnetism of Mn3Sn Studied by Polarized Neutron Diffraction

The magnetic structure and weak ferromagnetism of Mn 3 Sn were studied by polarized neutron diffraction at room temperature. The flipping ratio was measured for a number of Bragg reflections by rotating the crystal about the scattering vector under a magnetic field of 8 kOe applied perpendicular to the scattering vector. It was found that the spin structure has a triangular configuration of inverse geometry in the c -plane and the triangle rotates opposite to the rotation of the c -plane field component. From the analysis of the anisotropy energy it was shown that the triangle of inverse geometry is stabilized by the Dzyaloshinski-Moriya interaction and the weak ferromagnetic moment appears from the mechanism that each spin in the inverse triangle tilts slightly toward its easy axis. It was also shown that the weak ferromagnetic moment rotates just opposite to the rotation of the triangle.