Tuesday, December 10, 2019

Imaging of magnetic materials enhanced with new electron microscope concept


New microscope system for magnetic materials detection
Under the Japan Science and Technology Agency SENTAN program, the joint development team of Prof. Naoya Shibata at the University of Tokyo and JEOL Ltd. has developed an electron microscope that incorporates newly designed magnetic objective lenses. The new microscope achieves direct, atom resolved imaging of materials with sub-angstrom spatial resolution, with a residual magnetic field less than 0.2 mT at the sample position.

Why magnetic materials can not be analyzed through current lens systems

One crucial disadvantage of current magnetic condenser objective lens systems for atomic resolution STEMs is that the samples should be inserted into high magnetic fields of up 3 Tesla (T). Such high fields can severely hamper atomic resolution imaging of many important soft/ hard magnetic materials such as silicon steel because the strong field can greatly alter or even destroy the material’s magnetic and physical structure. Recently, the new development of magnetic materials has advanced speedily. As atomic-scale structural analysis is key to the aforementioned technology, a solution to this problem is overdue.

Configuration of the new magnetic field-free lens system

The joint team has developed a new magnetic field-free objective lens system, containing two round lenses positioned in an exact mirror-symmetric configuration with respect to the sample plane. This new lens system provides extremely small residual magnetic field levels at the sample position while placing the strongly excited front/back objective lenses close enough to the sample to obtain the short focal length condition is essential for atomic resolution imaging. Consequently, the residual magnetic fields induced near the sample center are much less than 0.2 mT, which is 10,000 times smaller than the field strengths resulting from conventional magnetic objective lenses used for atomic resolution TEM/ STEM imaging.

The newly developed electron microscope can be operated in the same manner as a conventional STEM. It is expected to further promote substantial research and development in various nanotechnology fields.

For more information, visit www.jeol.co.jp/en and www.u-tokyo.jp/en.

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