Study On Magnetism By High-pressure Deformation Of Non-collinear Antiferromagnet Of Single-crystal Mn₃Sn

In recent years,there has been an increasing focus on the unique physical properties exhibited by the strongly correlated Weyl semi-metal Mn₃Sn due to its special non-collinear antiferromagnetic structure that breaks the time inversion symmetry.One of these properties is magnetic anisotropy,which is essential in applications such as spintronics.Another one is the anomalous Hall effect（AHE）,which has a wide range of potential uses.In general,regulating the magnetic structure of Mn₃Sn has been achieved through variable temperature or isotropic high pressure.However,the challenge lies in how to effectively regulate it at room temperature.This article investigates Mn₃Sn as the primary research subject,with a focus on altering its magnetic properties through lattice distortion.The Mn₃Sn single crystal is prepared using the flux method,and anisotropic high-pressure deformation technology is applied to deliberately induce lattice distortion.This intentional deformation causes Mn₃Sn to transition from an in-plane weak ferromagnetic structure（IWFM）to an out-plane weak ferromagnetic structure（OWFM）,leading to a significant improvement in its magnetic properties.The detailed conclusions are as follows:We first obtained a centimeter-sized Mn₃Sn single crystal using the flux method.This single crystal has a metallic surface and a regular hexagonal cross-section,with all magnetic moments are arranged along the plane,and the magnetic moments in each cell are 120°,so that the magnetic moments in each cell cancel as a whole,thus showing the anisotropic behavior of internal antiferromagnetic and off-plane paramagnetic magnetism.Next,we controlled the magnetic properties of the Mn₃Sn single crystal by introducing lattice distortion through anisotropic high-pressure deformation technology.This allowed us to drive the magnetic moment of Mn to arrange from in-plane to out-plane,resulting in an out-plane weak ferromagnetic spin structure at room temperature.The benefits of this structure are significant as it improves the magnetic properties of Mn₃Sn.Following the deformation process,the residual magnetization of Mn₃Sn increased from0.005μ_B/f.u.to 0.056μ_B/f.u.—an eleven-fold increase—and the coercivity increased from 0 to 6.02 k Oe.Finally,we studied the regulation mechanism of anisotropic high-pressure deformation technology on the magnetic properties of Mn₃Sn single crystal and obtained the relationship between the"microstructure-magnetism"of Mn₃Sn.By implementing the anisotropic deformation strategy,atomic-scale distortion occurs,which affects the exchange coupling between Mn magnetic moments in the same plane and adjacent planes,resulting in the alignment of Mn magnetic moments out of the plane.While antiferromagnets have become a promising candidate for the next generation of spintronic devices due to their advantages of fast response and small stray field,their weak detectable signal strength is a significant problem.Based on the results of our study,we have demonstrated that using anisotropic high-pressure deformation technology to control the magnetic properties of Mn₃Sn at room temperature is a feasible approach that could lead to the development of more efficient spintronic devices in the future.