The formation and field response of head-to-head domain walls in curved permalloy wires, fabricated to contain a single antinotch, have been investigated using Lorentz microscopy. High spatial resolution maps of the vector induction distribution in domain walls close to the antinotch have been derived and compared with micromagnetic simulations. In wires of 10 nm thickness the walls are typically of a modified asymmetric transverse wall type. Their response to applied fields tangential to the wire at the antinotch location was studied. The way the wall structure changes depends on whether the field moves the wall away from or further into the notch. Higher fields are needed and much more distorted wall structures are observed in the latter case, indicating that the antinotch acts as an energy barrier for the domain wall.

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This work reports on the magnetic interlayer coupling between two amorphous CoFeB layers, separated by a thin Ru spacer. We observe an antiferromagnetic coupling which oscillates as a function of the Ru thickness x, with the second antiferromagnetic maximum found for x = 1.0 to 1.1 nm. We have studied the switching of a CoFeB/Ru/CoFeB trilayer for a Ru thickness of 1.1 nm and found that the coercivity depends on the net magnetic moment, i.e. the thickness difference of the two CoFeB layers. The antiferromagnetic coupling is almost independent on the annealing temperatures up to 300 • C while an annealing at 350 • C reduces the coupling and increases the coercivity, indicating the onset of crystallization. Used as a soft electrode in a magnetic tunnel junction, a high tunneling magnetoresistance of about 50%, a well defined plateau and a rectangular switching behavior is achieved.

In this work we study Al-oxide-based tunnel junctions with amorphous Co 60 Fe 20 B 20 and polycrystalline Co 90 Fe 10 ferromagnetic (FM) electrodes. Focus is given on the evolution of the tunnel magnetoresistance and barrier characteristics (resistance-area product, effective thickness, height, and asymmetry) as a function of the annealing temperature up to 400°C. Junctions with two CoFeB electrodes show the largest thermal stability of the tunnel magnetoresistance. Substituting firstly one and then both CoFeB electrodes with CoFe leads to an increasingly faster degradation of the spin-dependent transport upon annealing. The observed differences suggest an improved interface quality between the amorphous FM and the Al oxide.