182 research outputs found
Monopolelike probes for quantitative magnetic force microscopy: calibration and application
A local magnetization measurement was performed with a Magnetic Force
Microscope (MFM) to determine magnetization in domains of an exchange coupled
[Co/Pt]/Co/Ru multilayer with predominant perpendicular anisotropy. The
quantitative MFM measurements were conducted with an iron filled carbon
nanotube tip, which is shown to behave like a monopole. As a result we
determined an additional in-plane magnetization component of the multilayer,
which is explained by estimating the effective permeability of the sample
within the \mu*-method.Comment: 3 pages, 3 figure
Magnetization reversal and local switching fields of ferromagnetic Co/Pd microtubes with radial magnetization
Three-dimensional nanomagnetism is a rapidly growing field of research covering both noncollinear spin textures and curved magnetic geometries including microtubular structures. We spatially resolve the field-induced magnetization reversal of free-standing ferromagnetic microtubes utilizing multifrequency magnetic force microscopy (MFM). The microtubes are composed of Co/Pd multilayer films with perpendicular magnetic anisotropy that translates to an anisotropy with radial easy axis upon rolling-up. Simultaneously mapping the topography and the perpendicular magnetostatic force derivative, the relation between surface angle and local magnetization configuration is evaluated for a large number of locations with slopes exceeding 45 degrees. The angle-dependence of the switching field is concurrent with the Kondorsky model, i.e., the rolled-up nanomembrane behaves like a planar magnetic film with perpendicular anisotropy and a pinning dominated magnetization reversal. Additionally, we discuss methodological challenges when detecting magnetostatic force derivatives near steep surfaces
Human-Computer Interaction for BCI Games: Usability and User Experience
Brain-computer interfaces (BCI) come with a lot of issues, such as delays, bad recognition, long training times, and cumbersome hardware. Gamers are a large potential target group for this new interaction modality, but why would healthy subjects want to use it? BCI provides a combination of information and features that no other input modality can offer. But for general acceptance of this technology, usability and user experience will need to be taken into account when designing such systems. This paper discusses the consequences of applying knowledge from Human-Computer Interaction (HCI) to the design of BCI for games. The integration of HCI with BCI is illustrated by research examples and showcases, intended to take this promising technology out of the lab. Future research needs to move beyond feasibility tests, to prove that BCI is also applicable in realistic, real-world settings
Employing electro-mechanical analogies for co-resonantly coupled cantilever sensors
Understanding the behaviour of mechanical systems can be facilitated and
improved by employing electro-mechanical analogies. These analogies enable
the use of network analysis tools as well as purely analytical treatment of
the mechanical system translated into an electric circuit. Recently, we
developed a novel kind of sensor set-up based on two coupled cantilever beams
with matched resonance frequencies (co-resonant coupling) and possible
applications in magnetic force microscopy and cantilever
magnetometry. In order to analyse the sensor's behaviour in detail,
we describe it as an electric circuit model. Starting from a simplified
coupled harmonic oscillator model with neglected damping, we gradually
increase the complexity of the system by adding damping and interaction
elements. For each stage, various features of the coupled system are
discussed and compared to measured data obtained with a co-resonant sensor.
Furthermore, we show that the circuit model can be used to derive sensor
parameters which are essential for the evaluation of measured data. Finally,
the much more complex circuit representation of a bending beam is discussed,
revealing that the simplified circuit model of a coupled harmonic oscillator
is a very good representation of the sensor system
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