102 research outputs found
Current-Induced Dynamics and Chaos of Antiferromagnetic Bimerons
A magnetic bimeron is a topologically non-trivial spin texture carrying an
integer topological charge, which can be regarded as the counterpart of
skyrmion in easy-plane magnets. The controllable creation and manipulation of
bimerons are crucial for practical applications based on topological spin
textures. Here, we analytically and numerically study the dynamics of an
antiferromagnetic bimeron driven by a spin current. Numerical simulations
demonstrate that the spin current can create an isolated bimeron in the
antiferromagnetic thin film via the damping-like spin torque. The spin current
can also effectively drive the antiferromagnetic bimeron without a transverse
drift. The steady motion of an antiferromagnetic bimeron is analytically
derived and is in good agreement with the simulation results. Also, we find
that the alternating-current-induced motion of the antiferromagnetic bimeron
can be described by the Duffing equation due to the presence of the nonlinear
boundary-induced force. The associated chaotic behavior of the bimeron is
analyzed in terms of the Lyapunov exponents. Our results demonstrate the
inertial dynamics of an antiferromagnetic bimeron, and may provide useful
guidelines for building future bimeron-based spintronic devices.Comment: 6 pages, 4 figure
SurrealDriver: Designing Generative Driver Agent Simulation Framework in Urban Contexts based on Large Language Model
Simulation plays a critical role in the research and development of
autonomous driving and intelligent transportation systems. However, the current
simulation platforms exhibit limitations in the realism and diversity of agent
behaviors, which impede the transfer of simulation outcomes to the real world.
In this paper, we propose a generative driver agent simulation framework based
on large language models (LLMs), capable of perceiving complex traffic
scenarios and providing realistic driving maneuvers. Notably, we conducted
interviews with 24 drivers and used their detailed descriptions of driving
behavior as chain-of-thought prompts to develop a `coach agent' module, which
can evaluate and assist driver agents in accumulating driving experience and
developing human-like driving styles. Through practical simulation experiments
and user experiments, we validate the feasibility of this framework in
generating reliable driver agents and analyze the roles of each module. The
results show that the framework with full architect decreased the collision
rate by 81.04% and increased the human-likeness by 50%. Our research proposes
the first urban context driver agent simulation framework based on LLMs and
provides valuable insights into the future of agent simulation for complex
tasks.Comment: 12 pages, 8 figure
Picosecond electric-field-induced threshold switching in phase-change materials
Many chalcogenide glasses undergo a breakdown in electronic resistance above
a critical field strength. Known as threshold switching, this mechanism enables
field-induced crystallization in emerging phase-change memory. Purely
electronic as well as crystal nucleation assisted models have been employed to
explain the electronic breakdown. Here, picosecond electric pulses are used to
excite amorphous AgInSbTe. Field-dependent reversible
changes in conductivity and pulse-driven crystallization are observed. The
present results show that threshold switching can take place within the
electric pulse on sub-picosecond time-scales - faster than crystals can
nucleate. This supports purely electronic models of threshold switching and
reveals potential applications as an ultrafast electronic switch.Comment: 6 pages manuscript with 3 figures and 8 pages supplementary materia
Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites.
Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. This work shows the important role of light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cell efficiencies
Self-assembling subnanometer pores with unusual mass-transport properties
A long-standing aim in molecular self-assembly is the development of synthetic nanopores capable of mimicking the mass-transport characteristics of biological channels and pores. Here we report a strategy for enforcing the nanotubular assembly of rigid macrocycles in both the solid state and solution based on the interplay of multiple hydrogen-bonding and aromatic π − π stacking interactions. The resultant nanotubes have modifiable surfaces and inner pores of a uniform diameter defined by the constituent macrocycles. The self-assembling hydrophobic nanopores can mediate not only highly selective transmembrane ion transport, unprecedented for a synthetic nanopore, but also highly efficient transmembrane water permeability. These results establish a solid foundation for developing synthetically accessible, robust nanostructured systems with broad applications such as reconstituted mimicry of defined functions solely achieved by biological nanostructures, molecular sensing, and the fabrication of porous materials required for water purification and molecular separations
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