Researchers Propose New Method for Detecting Magnetic Nanosamples

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A research group led by Prof. XUE Fei in High Magnetic Field Laboratory, Chinese Academy of Sciences (CHMFL), recently proposed a new method for assembling magnetic nanosamples and a cantilever for dynamic cantilever magnetometry.

Image Caption: Dynamic Cantilever Magnetometer for detecting magnetic nanosamples: Transfer process of nanosample (Fig. 1-4); SEM image of nanosamples (Fig. 5); Assembling figure of nanosample and cantilever (Fig. 6); Change Δf in the frequency of the cantilever for the magnetic nanosample (Fig. 7). (Image by XU Feng)

Magnetic nanostructures are elemental components in many different areas, such as high-density magnetic recording, magnetic sensors, magnetic force detection, and biomedical sciences.

In these studies and applications, quantitative analysis of magnetic anisotropy, coercivity, and saturation magnetization of nanomagnetic structures is very important.

The researchers in Prof. XUE's group proposed a sample-preparation and sample-transfer method that allows dynamic cantilever magnetometry to be used to measure individual nanostructures with no particular shape requirements.

They used a dual-beam system consisting of a focused ion beam and a scanning electron microscope (SEM), on which a nanomanipulator is installed.

Magnetic domain inversion in the nanosample with a minimum magnetic moment of about 1.7×10-15 emu can be detected by dynamic cantilever magnetometry setup. This sensitivity for measuring magnetic moments suffices to detect magnetic inversion processes in individual sub-100-nm ferromagnetic samples, which is 107 times smaller than the sensitivity of commercial magnetometers, such as the MPMS products from Quantum Design.

This research demonstrates the unique ability of dynamic cantilever magnetometry to characterize the magnetization process of small samples, and shows the important potential application of dynamic cantilever magnetometer instrumentation in the magnetic study of nanosamples.

This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, the Technological Development Grant of Hefei Science Center of Chinese Academy of Sciences, and the Major Program of Development Foundation of Hefei Center for Physical Science and Technology.