Lorentz Microscopy and Small-Angle Electron Diffraction

Hiroshi Nakajima, Atsuhiro Kotani, Ken Harada and Shigeo Mori

Abstract: In this article we report an electron optical system for both Foucault imaging and small angle electron diffraction (SmAED) constructed using non-dedicated conventional transmission electron microscope (TEM). In this system, an objective mini-lens is utilized in order to make a crossover on the plane where a selected area aperture is located. The aperture works for an angular selecting of the Foucault mode. The illumination and the imaging optics can be controlled independently. The maximum camera length is estimated to be approximately 1300 m. Magnetic domain structures in the ferromagnetic metallic phase of La_0.7Sr_0.3MnO₃ using the present electron optical system were presented. In addition, in-situ observation of changes of magnetic domain structures by applying external magnetic fields revealed the formation processes of magnetic bubbles in the M-type hexaferrite.

Key words: Lorentz microscopy, small-angle electron diffraction, magnetic domains, in-situ observation