Ultrasensitive magnetostrictive responses at the pre-transitional rhombohedral side of ferromagnetic morphotropic phase boundary

Abstract: The morphotropic phase boundary (MPB) has been utilized extensively in ferroelectrics and recently been extended to ferromagnets, especially for the magnetostrictive materials. Here, guided by phenomenological theories and phase-field simulations, we proposed a design strategy for obtaining the ultrasensitive magnetoelastic response at the pre-transitional rhombohedral side of ferromagnetic MPB, by further flattening the energy landscape while maintaining large intrinsic magnetostriction. To validate this, we judiciously introduced the light-rare-earth-based Tb_0.1Pr_0.9 system to the Co-doped Tb_0.27Dy_0.73Fe₂ alloy, as Tb_0.1Pr_0.9 is an anisotropy compensation system with large intrinsic strains and the transition metal dopant of Co tends to optimize the magnetostriction. Phase-field modeling was used to determine the detailed magnetic domain evolution of the investigated multi-component Laves phase compounds, the results of which were compared with experimental results. At room temperature, an ultrahigh magnetoelastic response d₃₃ was found in Tb0.253Dy0.657Pr0.09(Fe0.9Co0.1)2 recompensation system especially at low fields, which is superior to that of the commercial Tb_0.27Dy_0.73Fe₂ (Terfenol-D) polycrystal. The ultrahigh magnetostrictive sensitivity, together with low raw material cost makes it one of the strongest candidates for magnetostriction applications. Graphic abstract: [Figure not available: see fulltext.]