Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

The optical and electrical properties of terbium(III) bis(phthalocyanine) (TbPc2) films on cobalt substrates were studied using variable angle spectroscopic ellipsometry (VASE) and current sensing atomic force microscopy (cs-AFM). Thin films of TbPc2 with a thickness between 18 nm and 87 nm were prepared by organic molecular beam deposition onto a cobalt layer grown by electron beam evaporation. The molecular orientation of the molecules on the metallic film was estimated from the analysis of the spectroscopic ellipsometry data. A detailed analysis of the AFM topography shows that the TbPc2 films consist of islands which increase in size with the thickness of the organic film. Furthermore, the cs-AFM technique allows local variations of the organic film topography to be correlated with electrical transport properties. Local current mapping as well as local I–V spectroscopy shows that despite the granular structure of the films, the electrical transport is uniform through the organic films on the microscale. The AFMbased electrical measurements allow the local charge carrier mobility of the TbPc2 thin films to be quantified with nanoscale resolution

Intelligenter Werkstückträger mit Inertialsensorik zum Überwachen und Optimieren von Fertigungsprozessen

This article reports on a system for the sensorial recording of process parameters on a workpiece by the example of the forming process of profile cross rolling. For this purpose, data such as workpiece speed and position as well as the axial movement of the workpiece are recorded with inertial sensors. An intelligent workpiece carrier was developed and equipped with micromechanical sensors. A microcontroller is used to process the sensor data and send it wirelessly to a computer or laptop. The system is powered by a rechargeable battery. In addition to the acceleration and rotation speed data, the temperature of the workpiece is recorded during the forming process

Light-induced magnetoresistance in solution-processed planar hybrid devices measured under ambient conditions

We report light-induced negative organic magnetoresistance (OMAR) measured in ambient atmosphere in solution-processed 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) planar hybrid devices with two different device architectures. Hybrid electronic devices with trench-isolated electrodes (HED-TIE) having a channel length of ca. 100 nm fabricated in this work and, for comparison, commercially available pre-structured organic field-effect transistor (OFET) substrates with a channel length of 20 µm were used. The magnitude of the photocurrent as well as the magnetoresistance was found to be higher for the HED-TIE devices because of the much smaller channel length of these devices compared to the OFETs. We attribute the observed light-induced negative magnetoresistance in TIPS-pentacene to the presence of electron–hole pairs under illumination as the magnetoresistive effect scales with the photocurrent. The magnetoresistance effect was found to diminish over time under ambient conditions compared to a freshly prepared sample. We propose that the much faster degradation of the magnetoresistance effect as compared to the photocurrent was due to the incorporation of water molecules in the TIPS-pentacene film

Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

The optical and electrical properties of terbium(III) bis(phthalocyanine) (TbPc2) films on cobalt substrates were studied using variable angle spectroscopic ellipsometry (VASE) and current sensing atomic force microscopy (cs-AFM). Thin films of TbPc2 with a thickness between 18 nm and 87 nm were prepared by organic molecular beam deposition onto a cobalt layer grown by electron beam evaporation. The molecular orientation of the molecules on the metallic film was estimated from the analysis of the spectroscopic ellipsometry data. A detailed analysis of the AFM topography shows that the TbPc2 films consist of islands which increase in size with the thickness of the organic film. Furthermore, the cs-AFM technique allows local variations of the organic film topography to be correlated with electrical transport properties. Local current mapping as well as local I–V spectroscopy shows that despite the granular structure of the films, the electrical transport is uniform through the organic films on the microscale. The AFM-based electrical measurements allow the local charge carrier mobility of the TbPc2 thin films to be quantified with nanoscale resolution

Highly tunable magnetic and magnetotransport properties of exchange coupled ferromagnet/antiferromagnet-based heterostructures

Antiferromagnets AFMs with zero net magnetization are proposed as active elements in future spintronic devices. Depending on the critical film thickness and measurement temperature, bimetallic Mn based alloys and transition metal oxide based AFMs can host various coexisting ordered, disordered, and frustrated AFM phases. Such coexisting phases in the exchange coupled ferromagnetic FM AFM based heterostructures can result in unusual magnetic and magnetotransport phenomena. Here, we integrate chemically disordered AFM amp; 947; IrMn3 thin films with coexisting AFM phases into complex exchange coupled MgO 001 amp; 947; Ni3Fe amp; 947; IrMn3 amp; 947; Ni3Fe CoO heterostructures and study the structural, magnetic, and magnetotransport properties in various magnetic field cooling states. In particular, we unveil the impact of rotating the relative orientation of the thermally disordered and reversible AFM moments with respect to the irreversible AFM moments on the magnetic and magnetotransport properties of the exchange coupled heterostructures. We further reveal that the persistence of thermally disordered and reversible AFM moments is crucial for achieving highly tunable magnetic properties and multilevel magnetoresistance states. We anticipate that the presented approach and the heterostructure architecture can be utilized in future spintronic devices to manipulate the thermally disordered and reversible AFM moments at the nanoscal