Magnetic properties of Ni-Mn-Ga-Co-Cu tetragonal martensites exhibiting magnetic shape memory effect

Magnetic properties of Ni 46 Mn 24 Ga 22 Co 4 Cu 4, (Ni 45 Mn 23 Ga 22 Co 5 Cu 5, Ni 46 Mn 22.5 Ga 23 Co 5 Cu 3.5 ) tetragonal martensites with c / a ≈ 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 K 1 (300 K)= − 1.95 ∙ 10 5 J ∙ m −3 ( K 2 < 6%| K 1 |, K 3 < 2%| K 1 |, M S (300 K) = 63 Am 2 /kg) was about 30% lower than in the non-doped Ni 50.5 Mn 30.4 Ga 19.1 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.