Local structure and magnetic order in Magnetic Weyl semimetal Mn₃Sn

Mn₃Sn, a noteworthy kagome-lattice magnetic Weyl semimetal, has recently drawn considerable attention due to its intriguing properties. Even at room temperature, Mn₃Sn exhibits a large anomalous Hall effect, and the presence of magnetic Weyl fermions has been verified by angle-resolved photo-emission spectroscopy (ARPES) and magnetoresistance measurements. In this talk, I will present a comprehensive analysis of crystal structure, magnetic order, and atomic/magnetic pair distribution function analysis using X-ray diffraction and neutron total scattering. Single crystal x-ray diffraction confirmed the hexagonal Mg₃Cd-type average structure at 293 K. The material undergoes a magnetic transition at T_N1 ≈ 420 K to a 120° antiferromagnetic order (k=0) and forms an incommensurate helical magnetic order below T_N2 ≈ 280 K with two propagation vectors, (0,0,0.0877) and (0,0,0.1049). These two propagation vectors exhibit opposite temperature dependence upon cooling, merging to one k vector and separating at lower temperatures. We further observed changes in the pair distribution function patterns associated with the commensurate-incommensurate magnetic transition. This work uncovers the structural and magnetic correlations in local and average length scales and sheds light on understanding the spin-lattice coupling in Mn₃Sn.