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The transport properties of Co 2 MnSi/ AlO x / Co-Fe magnetic tunnel junctions showing a tunnel magnetorestistance of 95% at low temperatures are discussed with respect to temperature-dependent magnetic moments at the Co 2 MnSi/ AlO x interface and electronic band structure effects. These junctions show a considerably larger temperature and bias voltage dependence of the tunneling magnetoresistance compared to Co-Fe -B/AlO x / Co-Fe-B junctions, although the effective spin polarization of Co 2 MnSi ͑66%͒ is larger than CoFe-B ͑60%͒. Especially, the tunnel magnetoresistance of the Co 2 MnSi based junctions becomes inverse for large bias voltages. With increasing atomic disorder of the interfacial Co 2 MnSi its magnetic moments decrease and show a stronger temperature dependence. Even for the best atomic ordering achieved the corresponding spin-wave parameters of Mn and Co at the Co 2 MnSi/ AlO x interface are significantly larger than expected for Co 2 MnSi bulk and also larger than the spin-wave parameters of Co and Fe at a Co-Fe-B / AlO x interface. The influence of enhanced interfacial magnon excitation in the Co 2 MnSi/ AlO x / Co-Fe junctions on their transport properties will be discussed as well as possible origins for the negative tunnel magnetoresistance at high bias voltages.

In the present paper we investigate whether the ion bombardment induced magnetic modifications in exchange biased bilayers are stable in time, whether the direction of the exchange bias can be set to any arbitrary (in-plane) direction by the ion bombardment and whether the exchange bias field can be changed in successive bombardment steps. These three fundamental characteristics are prerequisites for ion bombardment used for an efficient, practical, and stable magnetic patterning of exchange biased layer systems.

X-ray absorption spectroscopy stud ies of the [MnIllGCrlll)1' single-mo lecu le magnet deposited as a microcrystalline layer on go ld substrates are presented. The oxidation state of the manganese cente rs cha nges from Mnlll to Mn" due to irradiatio n with soft X-rays. The influence of the charge-neutralizing anions on the stability of [MnIll 6Crlll)1' aga inst soft X-ray exposure is investigated for the different a nions tetraphenylborate (BPh 4-), lactate (C3HS0 3-) and perchlorate «(10 4-), The exposure d e pendence of the radiation-induced reduction process is compared for [MnIllGCrlll)1' with the three different anions.

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.