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The study of the small, defined magnetic structures has attracted much attention due to interest in both technology applications and fundamental research in micromagnetism. Microcantilever torque magnetometry (MTM) is a promising new experimental technique for measuring such small magnetic features . One of the challenges of using this technique is to place the sample on the cantilever. In this work, we develop a new process for preparing patterned magnetic film on cantilever and show a primarily result of magnetic interactions in a paired magnetic bar measured by MTM. The process of patterning the magnetic film on the cantilever is following: (a) deposit a multilayer Au (200nm)/Cr (10nm) on cantilever, (b) patterning using a focused ion beam (FIB) milling, (c) magnetic film deposition through a mask, and (d) a lift-off process. Fig. 1 shows an example of the patterned cantilever with 300 dots of 500 nm in diameter using this process.
In order to understand the magnetic interaction between a pair of bars, we prepare a sample as shown in Fig. 2. A 7 μm x 7 μm x 30 nm Ni80Fe20 film was put on the top left corner of the MTM cantilever. The Ni80Fe20 film was then patterned by a FIB workstation into two single 7 μm x 3.5 μm x 30 nm bars by cutting a 50 nm gap in the center of the film [Fig. 2(a)]. After the measurement, the top bar was removed with FIB milling and just left a single 7 μm x 3.5 μm x 30 nm bar on the cantilever [Fig. 2(b)].