1,944 research outputs found
Force sensing with nanowire cantilevers
Nanometer-scale structures with high aspect ratio such as nanowires and
nanotubes combine low mechanical dissipation with high resonance frequencies,
making them ideal force transducers and scanning probes in applications
requiring the highest sensitivity. Such structures promise record force
sensitivities combined with ease of use in scanning probe microscopes. A wide
variety of possible material compositions and functionalizations is available,
allowing for the sensing of various kinds of forces with optimized sensitivity.
In addition, nanowires possess quasi-degenerate mechanical mode doublets, which
has allowed the demonstration of sensitive vectorial force and mass detection.
These developments have driven researchers to use nanowire cantilevers in
various force sensing applications, which include imaging of sample surface
topography, detection of optomechanical, electrical, and magnetic forces, and
magnetic resonance force microscopy. In this review, we discuss the motivation
behind using nanowires as force transducers, explain the methods of force
sensing with nanowire cantilevers, and give an overview of the experimental
progress and future prospects of the field
Antiferromagnetic s-d exchange coupling in GaMnAs
Measurements of coherent electron spin dynamics in
Ga(1-x)Mn(x)As/Al(0.4)Ga(0.6)As quantum wells with 0.0006% < x < 0.03% show an
antiferromagnetic (negative) exchange bewteen s-like conduction band electrons
and electrons localized in the d-shell of the Mn2+ impurities. The magnitude of
the s-d exchange parameter, N0 alpha, varies as a function of well width
indicative of a large and negative contribution due to kinetic exchange. In the
limit of no quantum confinement, N0 alpha extrapolates to -0.09 +/- 0.03 eV
indicating that antiferromagnetic s-d exchange is a bulk property of GaMnAs.
Measurements of the polarization-resolved photoluminescence show strong
discrepancy from a simple model of the exchange enhanced Zeeman splitting,
indicative of additional complexity in the exchange split valence band.Comment: 5 pages, 4 figures and one action figur
Supporting Early Career Researchers through Gender Action Plans. A Design and Methodological Toolkit
Electric field sensing with a scanning fiber-coupled quantum dot
We demonstrate the application of a fiber-coupled quantum-dot-in-a-tip as a
probe for scanning electric field microscopy. We map the out-of-plane component
of the electric field induced by a pair of electrodes by measurement of the
quantum-confined Stark effect induced on a quantum dot spectral line. Our
results are in agreement with finite element simulations of the experiment.
Furthermore, we present results from analytic calculations and simulations
which are relevant to any electric field sensor embedded in a dielectric tip.
In particular, we highlight the impact of the tip geometry on both the
resolution and sensitivity.Comment: 10 pages, 4 figure
Optimized single-shot laser ablation of concave mirror templates on optical fibers
We realize mirror templates on the tips of optical fibers using a single-shot
CO laser ablation procedure. We perform a systematic study of the influence
of the pulse power, pulse duration, and laser spot size on the radius of
curvature, depth, and diameter of the mirror templates. We find that these
geometrical characteristics can be tuned to a larger extent than has been
previously reported, and notably observe that compound convex-concave shapes
can be obtained. This detailed investigation should help further the
understanding of the physics of CO laser ablation processes and help
improve current models. We additionally identify regimes of ablation parameters
that lead to mirror templates with favorable geometries for use in cavity
quantum electrodynamics and optomechanics
Work-life interferences in the early academic career stages: The case of precarious researchers in Italy
This paper addresses the topic of work–life interferences in academic contexts. More specifically, it focuses on early career researchers in the Italian university system. The total availability required from those who work in the research sector is leading to significant transformations of the temporalities of work, especially among the new generation of researchers, whose condition is characterized by a higher degree of instability and uncertainty. Which are the experiences of the early career researchers in an academic context constituted by a growing competition for permanent positions and, as a consequence, by a greatly increased pressure? Which are the main gender differences? In what elements do Science, Technology, Engineering and Mathematics disciplines differ from Social Sciences and Humanities? The collected narratives reveal how the ongoing process of precarization is affecting both the everyday working activities and the private and family lives of early career researchers, with important consequences also on their future prospects
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