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The switching behavior of the amorphous CoFeB/Ru/CoFeB artificial antiferromagnet (AFi) at submicron sizes is investigated, where additional shape anisotropy and the mangnetostatic edge coupling are also considered. The AFi has an increased coercivity with respect to a single layer of amorphous CoFeB and switching asteroids comparable to single layers are observed in samples with a high new moment.

The influence of noble-gas ions on the structural and electronic properties of the barrier and the barrier/electrode interfaces and the transport properties of Co/Al2O3/Co magnetic tunneling junctions with Ar(super +) and He(super +)-irradiated tunneling barrier are investigated. The results are explained with respect to the energy-dependent penetration depth of He(super +) and Ar(super +) and their energy loss in the barrier.

The temperature and dielectric stability of magnetic tunnel junctions are important requirements for magnetic memory devices and their integration in the semiconductor process technology. The evolution of the tunneling magnetoresistance (TMR) and the voltage stability during annealing, and some physical processes leading to a degradation of the voltage stability is reported.

Scanning probe microscopy resist patterning was proposed for the fabrication of nanometer-scale thin carbon layers. Unlike conventional resist processing, which requires solvent resist elimination, the proposed approach involves direct nano-scaled pattern writing. Results indicate that local field-induced oxidation of the carbon layer beneath the tip causes trench formation.

Giant magnetoresistance (GMR) measurements for Co/Cu multilayered thin films during their growth facilitate the characterization of their electron transport and layer formation. The newly developed in situ magnetoresistance measurement technique identifies the correlation between the growth mechanism and GMR as a function of Co thickness, effectively. Mean free paths of electron transport and interface scattering determine the magnitude of GMR effect.

Ultrahigh vacuum scanning-tunneling-microscopy study of large mass movement in current carrying metallic films shows that local inhomogeneities of the electric field exist in thin films. The current carrying capacity of these films decrease at certain ranges of current densities as there is a runaway thermal fusing mechanism. Topographical changes such as current aligned grain growth, current induced faceting and complex mass flow divergences are also observed.

The magnetic field generated by a current on chip at the location of the spin dependent tunneling (SDT) element is calculated depending on the geometric parameters of the current line and for the critical current density. No magnetic stability of the Ru/CoFe hard magnetic layer based tunneling system was measured during unidirectional switching.

The temperature stability of magnetic tunnel junctions is an important requirement for the fabrication of magnetic memory devices and the integration in the semiconductor process technology. The temperature evolution of the tunneling magnetoresistance (TMR) and the structural properties by isochronal annealing experiments up to 750 K is investigated.

A study was conducted to analyze the dependence of the giant magnetoresistance effect on the interface structure in Fe/Cr multilayers. Magnetoresistivity and Mossbauer spectroscopy were utilized to carry out the analysis. Experimental results indicated that microstructural changes in the conversion electron Mossbauer spectroscopy correlated with the GMR measurements revealing an improvement of magnetoresistivity in the Fe/Cr mutilayers.

Voltage ramp experiments were applied to study the time dependent dielectric breakdown in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions. The results from measurements on two types of junctions showed the bottom pinned junction to exhibit in general slightly lower breakdown voltages and stronger magnon excitations in the inelastic electron tunneling ([d.sup.2]I/d[V.sup.2])-V spectra than the top pinned junctions.

Magnetron sputtered thin Co-Mn-Sb films are examined with respect to their element-specific magnetic properties. The ratio of the Co and Mn moments has not changed up to the transition temperature and the temperature dependence of the magnetic moments is described by the mean-field theory.

Magnetic tunnel junctions with two MgO barriers separated by a free CoFeB middle electrode are examined. The calculations have shown an oscillation of the conductance and the tunnel magnetoresistance (TMR) with respect to the middle layer thickness and for a given interlayer thickness the TMR and the conductance have oscillated with respect to the bias voltage.

A study was conducted to explore the transport properties of magnetic tunnel junctions with different (110)-textured Heusler alloy electrodes such as [Co.sub.2]MnSi, [Co.sub.2]FeSi or [Co.sub.2][Mn.sub.0.5][Fe.sub.0.5]Si, Al[O.sub.x] barrier, and Co-Fe counterelectrode. The results showed that the transport properties of the studied junctions are dominated by inelastic excitations and not by the electronic bandstructure.

The manipulation of the exchange bias (EB) in an IrMn/CoFe/Ru/CoFe trilayer, as it is used in magnetic tunnel junctions (MTJs), is examined. An IrMn/Py/Co/Cu/Co stack is shown to be more sensitive to the impact of ion bombardment (IB) than the Ru based artificial ferrimagnet.

The time-dependent dielectric breakdown is examined in Co-Fe-B/MgO/Co-Fe-B junctions by voltage ramp experiments and is focused on its dependence on the barrier thickness, junction area, polarity of the applied voltage, ramp speed and annealing temperature. The results have shown that the breakdown voltage has depended both on the polarity of the applied voltage and the annealing temperature.

The inversion of high tunnel magnetoresistance (TMR) ratio at certain bias voltages in Co-Heusler-based magnetic tunnel junctions (MTJs) is examined. The studies have shown that the observed negative TMR values are a band structure effect.

X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) are used for investigating the chemical and magnetic properties at the lower [Co.sub.40][Fe.sub.40][B.sub.20]/MgO interface of Co-Fe-B/Mg interlayer/MgO/Co-Fe-B magnetic tunnel junctions (MTJs). The B concentration in the Co-Fe-B has decreased with increasing annealing temperature, at least some of the B has diffused toward or into the MgO barrier and has formed a [Ba.sub.2][O.sub.3] oxide.

The chemical and magnetic properties of [Co.sub.2]MnSi bulk films are investigated and compared with the properties of [Co.sub.2]MnSi right at the interface to the [Al.sub.x]O barrier. The analysis has shown similar results for Co in the bulk and at the interface, whereas Mn indicated significant differences.

A study demonstrates that it is possible to measure an x-ray interference pattern with a purely magnetic grating patterned by ion bombardment induced magnetic patterning. A homogeneous rotational direction of the magnetization at the edges between bombarded and not bombarded areas is observed.

The effect of roughness and different degrees of texture on the interlayer and exchange bias coupling fields and on the resistance-area product (R by A) and temperature and bias dependence of conductance and high tunneling magnetoresistance (TMR) and spin valve magnetic tunnel junctions (SV-MTJs) is examined. The results have implied that composition of buffer layers and their sequence can be used as one of the ways to improve the magnetic and tunneling properties of IrMn SV-MTJs.

An experimental demonstration is conducted of the feasibility of reprogrammable logic gate arrays, based on magnetic tunnel junctions. The junctions are realized with different tunneling systems and are investigated magnetically and electrically.

The magnetic and chemical interface properties of Mn-Ir/Co-Fe/Al+oxidation/Ni-Fe magnetic tunnel junction is investigated for different barrier thickness, oxidation times, and annealing conditions. For optimally oxidized and overoxidized samples, FeO(subx) is formed during oxidation, which is reduced by Mn diffusing t the barrier during annealing.

Research is done on a low dielectric constant polyarylether (PAE) polymer, which was investigated for resistance to copper drift. Finally, a combination of BTS and TVS techniques is found to be more useful for characterization of copper drift, and helps to resolve the intrinsic polymer effect from that of metal drift-related instability.

Research is done on hard magnetic (HM) thin films, which have been vertically integrated below giant magnetoresistive (GMR) multilayer sensors in order to shift the operating point of an applicable GMR sensor. In conclusion, the MR response signal of biased multilayers can be understood using numerical measurements.

The magnetically hard electrode's exchange bias was manipulated in magnetic tunnel junctions by bombarding them with 10-20 keVHe (super +1)ions in an applied magnetic field. The findings show that the tunneling magnetoresistance decreases for very high doses while the area resistance product increases.

The size dependence of switching properties of free layers in magnetic tunnel junctions is explained. A model taking account of both Neel-type and dipole coupling quantitatively explains the dependence of the shift.

The role of the microstructure and the magnetic behavior of Co2MnSi thin films prepared, at room temperature, using dc magnetron sputtering is determined. Due to the high resistivity of these films, Co2MnSi serves as electrodes in tunnel magnetoresistance structures.

Tailoring magnetic nanocrystal superlattices by chemical engineering are discussed. The measured composition of these FeCo nanoparticles with increasing diameter suggests that their structure is onion like, with an Fe core surrounded by shell with increasing Co content.

Magnetic and Mossbauer spectroscopy studies of Fe/Si multilayers is discussed. The QS doublet is a minor spectral component it is difficult to identify clearly from the QS and IS values which FeSi-type phase appears in our Fe/Si MIs.

Structural imperfections on the nanometer scale act as imperfect corners and rough electrode boundaries cause junction specific magnetic switching behavior. Micromagnetic numerical simulations with the real atomic force microscopy (AFM) shape show that these individual details significantly influence the nucleation, location, and mobility of domain walls.

The evolution of the magnetic interlayer interaction by annealing and its related microstructural changes in the film stacks, which are identified by Auger depth profiling and complementary methods, is discussed. The microstructural investigation gives evidence that small ferromagnetic clusters arise in the hard layer of the junctions by diffusion of Cu, Co, and Fe.

The structural, the magnetic, the magnetotransport, and the tunneling properties of CoFe/Al(sub 2)O(sub 3)/Ni(sub 81)Fe(sub 19) junctions with an artificial ferrimagnet as a pinning layer for different Al thickness and oxidation time after isochronal annealing up to 500 degrees C, was investigated. Thermally induced structural changes of the microstructure, determined by Auger depth profiling and complementary methods, were observed.

The study reports the result obtained for giant magnetoresistance multilayers mixed systems, containing simultaneously the first and the second maximum of the antiferromagnetic coupling. Both a phenomenological numerical approach as well as experimental results demonstrates that such systems can be used for tailoring new shapes of GMR curves.

The interplay of different adjacent antiferromagnetic coupling constants in combination multilayers is classified in two regimes. The giant magnetoresistance characteristic of the simplest CML with N=1 is determined by averaging the bilinear and biquadratic exchange coupling constants of the two base systems.

By using phase-resolved micro-focus Brillouin light scattering spectroscopy, we demonstrate experimentally a phenomenon of wavelength conversion of spin waves propagating in tapered Permalloy waveguides. We show that this phenomenon enables efficient excitation of spin waves with sub-micrometer wavelengths being much smaller than the width of the microstrip antenna used for the excitation. The proposed excitation mechanism removes restrictions on the spin-wave wavelength imposed by the size of the antenna and enables improvement of performances of integrated magnonic devices. [ABSTRACT FROM AUTHOR]

The influence of a postannealing procedure on the transport properties of magnetic tunnel junctions with ion-bombardment-manipulated exchange bias is investigated. The controlled manipulation of the direction of the exchange bias field in magnetic tunnel junctions by He ion bombardment usually is accompanied by a reduction of the tunneling magnetoresistance and an increase in the resistance. Here, we demonstrate that it is possible to reduce these negative effects of the ion bombardment considerably by postannealing without a magnetic field. For optimized combinations of ion dose and postannealing temperature, the tunneling magnetoresistance recovers completely (>50% resistance change) while the exchange bias direction set by the ion bombardement is preserved. [ABSTRACT FROM AUTHOR]

Spintronics needs half-metallic materials implemented in technologically relevant devices. We prepare Co2MnSi/AlOx/Co7Fe3 junctions showing a tunneling magnetoresistance of 94.6% at 1 mV and 20 K. Their inelastic electron tunneling spectra at 20 K show typical magnon and phonon excitations in the electrode and the barrier and an additional shoulder around -22 mV not observed in Co7Fe3/AlOx/Ni81Fe19 reference junctions. Furthermore, the bias voltage and temperature dependence of the tunneling magnetoresistance is considerably larger than for the reference junctions. The transport properties are discussed with respect to a variety of current contributions associated with the structural and magnetic properties of the Co2MnSi/AlOx interface. [ABSTRACT FROM AUTHOR]