Typed-new multifunctional Mn-rich antiferromagnetic alloys

The lattice distortion of crystal structure can be formed and following fct martensitic transformation is induced with antiferromagnetic transition in Mn-rich antiferromagnetic alloys. The twin boundaries formed with fct martensitic transformation or tiny twin (antiferromagnetic domain boundaries) with antiferromagnetic transition have mobility and high damping property can be obtained under an alternate stress. With the help of the coupling between the second order antiferromagnetic transition and the first order martensitic transformation, the hysteresis between martensitic transformation and reversible one is decreased or even is disappeared, the martensitic transformation temperature, Ms, and its reversible transformation temperature, As, move closer to antiferromagnetic transition point, Tn, the shape memory effect formed by martensitic transformation and its reversible one may be related with a simplex temperature function and a non-hysteresis on temperature can be formed. Because the tiny twin boundaries and the fct twin boundaries have movability under applied magnetic field, the magneto-driven strain and magneto-controlled shape memory effect may be shown. Now the new-typed multifunctional antiferromagnetic materials are being researched and developed in theoretically and practically.