Rapid screening of magnetic properties in several Fe-X-Ni systems via combinatorial materials chip method

Fe-X-Ni (X = Cr, W and V) combinatorial thin-film (∼100 nm thick) materials chips covering the full composition range of ternary systems were fabricated. The crystal structure distribution was mapped by micro-beam X-ray diffractometers (XRD) and the magnetic hysteresis loops over the chip were characterized by a high-throughput magneto-optical Kerr effect (HT-MOKE) system to establish the composition-phase-magnetic properties relationships. The results showed that saturation magnetization for all systems has a strong dependency on alloying composition, and decreases with increasing dopped elements content as a general trend. Although the trend of saturation magnetization in bulk is in good agreement with that from thin films, all bulk samples show almost no coercivity, attributable to the much smaller grain size, and stronger texture in thin-film samples. Comparing the Fe-X-Ni systems under a similar condition, in the out-of-plane, Cr alloying obtained the largest coercivity (∼400 mT) followed by W alloying (∼300 mT) and then V alloying (∼200 mT). We suggest that alloying with different elements leads to the diverse orientation and crystallinity of the fcc phase resulting in different magnetic properties. Meanwhile, the effect of heat treatment on magnetic properties indicates that saturation magnetization is more closely related to the duration of heat treatment.