Structural properties and magnetic behavior in CoFe1−xAlx alloys

Atomic disorder and magnetic property in Co-based Heusler alloys Co2MnZ (Z=Si, Ge, Sn)

“…Heat treatments are the same as mentioned above. Their mean magnetic moments were obtained from the saturation magneti- zation measurement at 4.2 K in the magnetic fields of 20-30 kOe by using a SQUID magnetometer, in a similar way as reported previously [10].…”

“…The point defect structure in the Co2YZ-type Heusler alloy can be described by specifying nine concentrations of constituent atoms on respective sites [10]: three for the right atoms, e.g., Co atom on the Co-site, and six for the antisite atoms, e.g., Y atom on the Z-site and Z atom on the Y-site. Among these, number of the independent variables is four, so that four long-range order (LRO) parameters are generally needed for description of the defect structure.…”

“…Among these, number of the independent variables is four, so that four long-range order (LRO) parameters are generally needed for description of the defect structure. Here, for simplicity, we will follow the defect model adopted in our previous studies for CoFe1−xAlx Heusler alloys [10,11], which is based on the model proposed by Webster [12] in neutron diffraction study. Then, the number of the LRO-parameters is reduced to two.…”

“…Then, the number of the LRO-parameters is reduced to two. In the CoY1−xZx alloy case, they are given by [10]:…”

“…Recently, we have studied experimentally the magnetic behavior and the atomic disorder in B2-type Co 1−x Fe x alloys (0.4 ≤ x ≤ 0.6) [8,9] and B2-and Heusler-type CoFe 1−x Al x alloys (0 ≤ x ≤ 1) [10,11] by quenching them from various temperatures. In B2-phase Co 1−x Fe x and CoFe 1−x Al x alloys, it was shown that proceeding of atomic disorder on the Co-site, Co-type disorder, due to increase in quenching temperature leads to a certain decrease in their mean magnetic moment, i.e., the Co-type disorder leads to degradation of the magnetism.…”