Shape dependence of the magnetization reversal in sub-μm magnetic tunnel junctions

In order to get access to resistance of very small junctions with lateral sizes down to 100 nm and below, we have set up a home-built conducting atomic force microscope which is able to contact the individual junctions with the tip and measure the tunnel magnetoresistance (TMR). The junctions are patterned by standard electron beam lithography. The influence of the element shape is investigated by analysing their switching behaviour in TMR minor loops and asteroids. In addition, numerical simulations of the magnetization reversal are carried out and compared to the experiment