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

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 $$\hbox {Tb}_0.1\hbox {Pr}_0.9$$ system to the Co-doped $$\hbox {Tb}_0.27\hbox {Dy}_0.73\hbox {Fe}₂$$ alloy, as $$\hbox {Tb}_0.1\hbox {Pr}_0.9$$ 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 $${d}₃₃$$ was found in $$\hbox {Tb}_0.253\hbox {Dy}_0.657\hbox {Pr}_0.09(\hbox {Fe}_0.9\hbox {Co}_0.1)₂$$ recompensation system especially at low fields, which is superior to that of the commercial $$\hbox {Tb}_0.27\hbox {Dy}_0.73\hbox {Fe}₂$$ (Terfenol-D) polycrystal. The ultrahigh magnetostrictive sensitivity, together with low raw material cost makes it one of the strongest candidates for magnetostriction applications.