Energy filtered magnetic domain imaging at 400 kV

Abstract

Lorentz microscopy provides an important technique for the study of advanced magnetic recording media. Recording densities as high as 10 Gbit/in may be within reach in the future. Microstructural characterization of both the crystallographic and magnetic structure of these thin films is needed at the highest spatial resolution. Another area where Lorentz microscopy has proven to be an extremely valuable tool is in magnetic actuator applications, in particular for magnetostrictive alloys, such as Terfenol-D. The standard Lorentz techniques (Fresnel and Foucault imaging) require a low-field environment, so that the sample is not completely saturated during observations. Depending on the microscope type this low-field area can be obtained by either switching off the objective lens and using the weak post-field to focus the image, or by using special low-field pole pieces. The attainable magnification in both cases is usually lower than for conventional TEM. Recently a new low-field lens for the JEOL 4000EX TEM was reported (AMG40, 1 Gauss field strength) with a useful magnification range upto × 200,000. In this paper we report an alternative method to obtain high magnification magnetic domain images at 400 kV.