Magnetic properties of Ni-Mn-Ga-Co-Cu tetragonal martensites exhibiting magnetic shape memory effect
Abstrakt
Magnetic properties of Ni46Mn24Ga22Co4Cu4, (Ni45Mn23Ga22Co5Cu5, Ni46Mn22.5Ga23Co5Cu3.5) tetragonal martensites with c/a ALMOST EQUAL TO 1.14 exhibiting near 10% magnetic field-induced strain (MFIS) were investigated between 10 and 500 K and up to 9 T field. The (001) easy plane magnetocrystalline anisotropy with K1(300 K)= MINUS SIGN 1.95 BULLET OPERATOR 105 J BULLET OPERATOR mMINUS SIGN 3 (K2 < 6%|K1|, K3 < 2%|K1|, MS(300 K) = 63 Am2/kg) was about 30% lower than in the non-doped Ni50.5Mn30.4Ga19.1 reference, which can be related to a reduced c/a ratio in the doped material.
In spite of different type of magnetocrystalline anisotropy compared to 10M martensite, the mechanism of MFIS is the same, i.e. with the typical first-quadrant magnetization hysteresis and {101} twin boundary motion.