Room Temperature Giant Magnetostriction in Ultrathin Fe_xMn_1-xGa₄

Developing ultrathin giant magnetostrictive materials above room temperature creates a versatile platform for straintronic and spintronic applications because they can provide significant spin-lattice interaction on the nanoscale. Nevertheless, due to the suppression of magnetic ordering by thermal fluctuations, there are fewer ultrathin room-temperature magnetic materials available, not to mention ultrathin giant magnetostrictive materials at room temperature. Here, the ultrathin single-crystal Fe_xMn_1-xGa₄ is reported with above-room-temperature Curie temperature (T_C, ≈ 324 K) and giant magnetostriction (magnetostrictive coefficient λ, -1670 ppm). The giant magnetostriction originates from the large magnetic anisotropy energy of Fe_xMn_1-xGa₄, which is caused by the strong spin coupling between d_xy and d_yz of Fe atoms due to the same spin channel near the Fermi level. The Villari effect is also observed in the Fe_xMn_1-xGa₄, in which the coercivity field increases dramatically by more than 300% at a tiny-scale applied strain of 0.69%. This work provides an avenue to realize giant magnetostriction in ultrathin materials at room temperature, laying the foundation for low-power-consumption, integrative, and high-performance nanoelectromechanical applications.