28 research outputs found
Formation of colloidal alloy semiconductor CdTeSe magic-size clusters at room temperature
Alloy magic-size clusters (MSCs) are difficult to synthesize, in part because so little is known about how they form. Here, the authors produce single-ensemble alloy CdTeSe MSCs at room temperature by mixing prenucleation-stage solutions of CdTe and CdSe, uncovering a formation pathway that may extend to the synthesis of other alloy MSCs
Recommended from our members
The effect of degree of reduction on the electrical properties of functionalized graphene sheets
We study the effect of carbon to oxygen ratio (C/O) on the electrical resistance of functionalized
graphene sheets prepared by thermal exfoliation and reduction of graphite oxide at various
temperatures. Using a 2-probe technique in conjunction with Kelvin probe force microscopy, we
observe a transition from high-resistance (>400 kX/sq) nonlinear current/voltage characteristics at
low C/O to low-resistance (<10 kX/sq) linear behavior at high C/O, indicating a transition from
hopping to diffusive electron transport. Simultaneously, the metal-graphene contacts change from
high-resistance Schottky-type behavior to nearly non-invasive metal-metal contact characteristics
Digital Doping in Magic-Sized CdSe Clusters
Magic-sized semiconductor clusters represent an exciting class of materials located at the boundary between quantum dots and molecules. It is expected that replacing single atoms of the host crystal with individual dopants in a one-by-one fashion can lead to unique modifications of the material properties. Here, we demonstrate the dependence of the magneto-optical response of (CdSe)13 clusters on the discrete number of Mn2+ ion dopants. Using time-of-flight mass spectrometry, we are able to distinguish undoped, monodoped, and bidoped cluster species, allowing for an extraction of the relative amount of each species for a specific average doping concentration. A giant magneto-optical response is observed up to room temperature with clear evidence that exclusively monodoped clusters are magneto-optically active, whereas the Mn2+ ions in bidoped clusters couple antiferromagnetically and are magneto-optically passive. Mn2+-doped clusters therefore represent a system where magneto-optical functionality is caused by solitary dopants, which might be beneficial for future solotronic applications. © 2016 American Chemical Society116151sciescopu
Development and application of test methods for the detection of dietary constituents which protect against heterocyclic aromatic amines
International audienc
Experimental identification of two distinct skyrmion collapse mechanisms
Magnetic skyrmions are key candidates for novel memory, logic, and
neuromorphic computing. An essential property is their topological protection
caused by the whirling spin texture as described by a robust integer winding
number. However, the realization on an atomic lattice leaves a loophole for
switching the winding number via concerted rotation of individual spins. Hence,
understanding the unwinding microscopically is key to enhance skyrmion
stability. Here, we use spin polarized scanning tunneling microscopy to probe
skyrmion annihilation by individual hot electrons and obtain maps of the
transition rate on the nanometer scale. By applying an in-plane magnetic field,
we tune the collapse rate by up to four orders of magnitude. In comparison with
first-principles based atomistic spin simulations, the experiments demonstrate
a radial symmetric collapse at zero in-plane magnetic field and a transition to
the recently predicted chimera collapse at finite in-plane field. Our work
opens the route to design criteria for skyrmion switches and improved skyrmion
stability.Comment: 11 pages, 6 figure
Prioritization of intensive medical treatment places - Concept proposal
In the situation of a shortage of ventilation beds, ethically justifiable, transparent and comprehensible decisions must be made. This concept proposes that all patients are first intubated depending on necessity and then assessed by a triage team afterwards. In this situation newly admitted COVID patients compete with newly admitted Non-COVID patients as well as patients already treated in intensive care units for a ventilator. The combination of short-term and long-term prognoses should enable the interprofessional triage team to make comprehensible decisions. The aim of the prioritization concept is to save as many human lives as possible and to relieve the treatment team of the difficult decision on prioritization