Giant Non-Saturating Exchange Striction in a Noncollinear Antiferromagnet

Magnetostriction, discovered by Joule in 1842, refers to the mechanical strain that a material undergoes in the presence of a magnetic field. Conventionally, it originates from the spin-orbit coupling and has been predominantly explored in ferromagnets. In this work, a giant magnetostriction effect is reported in the high-quality single crystal of a noncollinear antiferromagnet Mn₃Sn. Non-saturating magnetostriction exceeding 400 ppm is obtained, which is even larger than the saturation values of the well-known Fe-based giant magnetostriction ferromagnetic materials such as FeGa. Theoretical calculations reveal that the large non-saturating magnetostriction results from a sophisticated exchange striction effect of the noncollinear antiferromagnetic spin structure, leading to a nearly linear dependence of the strain output on the applied magnetic field. This work provides an unprecedented strategy to design next-generation magnetoelastic materials with noncollinear compensated spin structures.