605 research outputs found
Dynamic screening of quasiparticles in WS monolayers
We unravel the influence of quasiparticle screening in the non-equilibrium
exciton dynamics of monolayer WS. We report pump photon energy-dependent
exciton blue/red-shifts from time-resolved-reflectance contrast measurements.
Based on a phenomenological model, we isolate the effective impact of excitons
and free carriers on the renormalization of the quasi-free particle band gap,
exciton binding energy and linewidth broadening. This work provides a
comprehensive picture of the competing phenomena governing the exciton dynamics
in WS upon photoexcitation
Energy-efficient domain wall motion governed by the interplay of helicity-dependent optical effect and spin-orbit torque
Spin-orbit torque provides a powerful means of manipulating domain walls
along magnetic wires. However, the current density required for domain wall
motion is still too high to realize low power devices. Here we experimentally
demonstrate helicity-dependent domain wall motion by combining synchronized
femtosecond laser pulses and short current pulses in Co/Ni/Co ultra-thin film
wires with perpendicular magnetization. Domain wall can remain pinned under one
laser circular helicity while depinned by the opposite circular helicity.
Thanks to the all-optical helicity-dependent effect, the threshold current
density due to spin-orbit torque can be reduced by more than 50%. Based on this
joint effect combining spin-orbit torque and helicity-dependent laser pulses,
an optoelectronic logic-in-memory device has been experimentally demonstrated.
This work enables a new class of low power spintronic-photonic devices beyond
the conventional approach of all-optical switching or all-current switching for
data storage.Comment: 21 pages, 5 figure
6G Non-Terrestrial Networks Enabled Low-Altitude Economy: Opportunities and Challenges
The unprecedented development of non-terrestrial networks (NTN) utilizes the
low-altitude airspace for commercial and social flying activities. The
integration of NTN and terres- trial networks leads to the emergence of
low-altitude economy (LAE). A series of LAE application scenarios are enabled
by the sensing, communication, and transportation functionalities of the
aircrafts. The prerequisite technologies supporting LAE are introduced in this
paper, including the network coverage and aircrafts detection. The LAE
functionalities assisted by aircrafts with respect to sensing and communication
are then summarized, including the terrestrial and non-terrestrial targets
sensing, ubiquitous coverage, relaying, and traffic offloading. Finally,
several future directions are identified, including aircrafts collaboration,
energy efficiency, and artificial intelligence enabled LAE.Comment: This paper has been submitted to IEEE for possible publicatio
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