Switching Behaviour of Sub-Micron Magnetic Elements Studied By Tem

Extract

Magnetic elements in the micron and sub-micron size range are important for application as discrete bits in high density storage systems and as the active part of ultra-small magnetic sensors of the kind required in read heads. Patterning techniques based around electron beam lithography are used to fabricate elements with different sizes and shapes and TEM allows the magnetisation distributions they support to be investigated. Figure 1 shows a regular domain structure in a rectangular element of length 1μm. Of particular importance is the ability to observe directly how the elements respond to an applied field and thereby to gain information on magnetisation processes. When the fields required are in excess of a few 100 Oe, it is most convenient to use the vertical field of the objective lens. Field components in the specimen plane are then generated by tilting. For this technique to be effective it must be possible to choose an objective field strength appropriate to the elements under study and to have separate non-immersion lenses (Lorentz lenses) as the primary imaging or probeforming components.