Magnetic anisotropy in Ni–Fe–Ga–Co ferromagnetic shape memory alloys in the single-variant state
Magnetic anisotropy in Ni–Fe–Ga–Co ferromagnetic shape memory alloys in the single-variant state
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DOI：
10.1088/0953-8984/21/7/076001
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
H. Morito;A. Fujita;K. Oikawa;K. Fukamichi;R. Kainuma;T. Kanomata;K. Ishida
中科院分区：
文献类型：
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作者：
H. Morito;A. Fujita;K. Oikawa;K. Fukamichi;R. Kainuma;T. Kanomata;K. Ishida
研究了Co对Ni 55 − xFe 18 Ga 27 Cox（x = 1-6）单变量铁磁形状记忆合金磁各向异性的影响。通过添加1至6原子%的Co，居里温度TC从318 K增加到405 K，保持马氏体转变温度高于室温。因此，单轴磁各向异性常数的值|Ku|在300 K时，随着Co浓度x的增加，Ni 49 Fe 18 Ga 27 Co 6的马氏体相表现出相对高的|Ku| = 1.15 × 105 J m-3（300 K）。另一方面，随着Co浓度的增加，c轴在4.2K下从易磁化轴变为难磁化轴，即Ku的符号在2和3at.%之间从正变为负。此外，Ni 53 Fe 18 Ga 27 Co 2中的Ku在低于100 K时为正，在高于100 K时为负，直到TC，降低了200 K附近的磁各向异性。从目前的结果来看，很明显，Ni 55-xFe 18 Ga 27 Cox（x = 1-6）单变量铁磁形状记忆合金的磁各向异性对Co浓度和温度非常敏感。
The effects of the addition of Co on the magnetic anisotropy in Ni55−xFe18Ga27Cox (x = 1–6) single-variant ferromagnetic shape memory alloys have been investigated. By the addition of Co from 1 to 6 at.%, the Curie temperature TC is increased from 318 to 405 K, keeping the martensitic transformation temperatures above room temperature. As a result, the value of the uniaxial magnetic anisotropy constant |Ku| at 300 K increases with increasing x of the Co concentration and the martensite phase of Ni49Fe18Ga27Co6 exhibits a relatively high value of |Ku| = 1.15 × 105 J m−3 at 300 K. With increasing Co concentration, on the other hand, the c axis changes from the magnetic easy axis to the hard axis at 4.2 K, that is, the sign of Ku is reversed from positive to negative between 2 and 3 at.% Co. Furthermore, Ku in Ni53Fe18Ga27Co2 is positive below 100 K and negative above 100 K up to TC, reducing the magnetic anisotropy around 200 K. From the present results, it is evident that the magnetic anisotropy of Ni55−xFe18Ga27Cox (x = 1–6) single-variant ferromagnetic shape memory alloys is very sensitive to Co concentration and also temperature.