Effect of Cu addition on the crystal structure and magnetic properties for Mn-Ga thin films

Rare earth magnets are known to possess high maximum energy products and a large magnetic moment. However, the countries of origin of those rare earth elements are unevenly distributed, and they are expensive and anxious about sustainable supply. Therefore, there is a need to develop rare-earth-free permanent magnets. Mn-Ga alloy films with L1
0
structure have attracted much attention for application to rare-earth-free permanent magnets and spin-transfer-torque magnetoresistive random access memory (STT-MRAM). In this study, In order to see the effect of Cu addition on the crystal structure and magnetic properties of L1
0
Mn-Ga thin films have been investigated. The samples were prepared on MgO (100) single crystal substrates using an ultra-high vacuum magnetron sputtering system. It was found that the addition of a small amount of Cu (0.75 ~ 1.5 vol. %) increased the peak intensity attributed to the L1
0
phase, but further addition resulted in a decrease in peak intensity and the value of saturation magnetization increased from 529 in w/o Cu to 637 emu/cm
³
in 0.75, 1.5 vol. % Cu. However, the value of coercivity was decreased by the addition of small amount of Cu.