Preparation of Ni-Mn-Ga Micropillars Using Focused Xe-ion Beam Milling for Magnetic Actuation on Microscale

Magnetic shape memory alloys are promising candidates for actuation on microscale. We investigate the possibility of using focused Xe-ion (as an alternative to Ga-ion) beam milling (Xe-FIB) for microfabrication on Ni-Mn-Ga magnetic shape memory single crystals. We started with the most basic structures such as micropillars. Xe-FIB working conditions of 30 kV/100 nA results in large curtaining effect thus for micrometre sized structures a two-step milling procedure was used with the final polishing conditions of 30 kV/100 pA. Pillars down to 1 micrometre size were produced; preparation of 10 x 10 micrometres square-base pillar for magnetomechanical testing is illustrated in individual steps. By the combination of mechanical testing and optical microscopy we demonstrate that the Xe-FIB milling does not significantly change the ability of martensite twin boundaries to propagate through the fabricated pillars.