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Abstract In the burgeoning field of spintronics, antiferromagnetic materials (AFMs) are attracting significant attention for their potential to enable ultra‐fast, energy‐efficient devices. Thin films of AFMs are particularly promising for practical applications due to their compatibility with spin‐orbit torque (SOT) mechanisms. However, studying these thin films presents challenges, primarily due to the weak signals they produce and the rapid dynamics driven by SOT, that are too fast for conventional electric transport or microwave techniques to capture. The time‐resolved magneto‐optical Kerr effect (TR‐MOKE) has been a successful tool for probing antiferromagnetic dynamics in bulk materials, thanks to its sub‐picosecond (sub‐ps) time resolution. Yet, its application to nanometer‐scale thin films has been limited by the difficulty of detecting weak signals in such small volumes. In this study, the first successful observation of antiferromagnetic dynamics are presented in nanometer‐thick orthoferrite films using the pump‐probe technique to detect TR‐MOKE signal. This paper report an exceptionally low damping constant of 1.5 × 10⁻⁴and confirms the AFM magnonic nature of these dynamics through angular‐dependent measurements. Furthermore, it is observed that electrical currents can potentially modulate these dynamics via SOT. The findings lay the groundwork for developing tunable, energy‐efficient spintronic devices, paving the way for advancements in next‐generation spintronic applications. 

Abstract Achieving spin-pinning at the interface of hetero-bilayer ferromagnet/antiferromagnet structures in conventional exchange bias systems can be challenging due to difficulties in interface control and the weakening of spin-pinning caused by poor interface quality. In this work, we propose an alternative approach to stabilize the exchange interaction at the interface of an uncompensated antiferromagnet by utilizing a gradient of interlayer exchange coupling. We demonstrate this exchange interaction through a designed field training protocol in the odd-layer topological antiferromagnet MnBi₂Te₄. Our results reveal a remarkable field-trained exchange bias of up to ~ 400 mT, which exhibits high repeatability and can be easily reset by a large training field. Notably, this field-trained exchange bias effect persists even with zero-field initialization, presenting a stark contrast to the traditional field-cooled exchange bias. The highly tunable exchange bias observed in this single antiferromagnet compound, without the need for an additional magnetic layer, provides valuable insight into the exchange interaction mechanism. These findings pave the way for the systematic design of topological antiferromagnetic spintronics. 

The latest developments in vehicle-to-infrastructure (V2I) and vehicle-to-anything (V2X) technologies enable all the entities in the transportation system to communicate and collaborate to optimize transportation safety, mobility, and equity at the system level. On the other hand, the community of researchers and developers is becoming aware of the critical role of roadway infrastructure in realizing automated driving. In particular, intelligent infrastructure systems, which leverage modern sensors, artificial intelligence, and communication capabilities, can provide critical information and control support to connected and/or automated vehicles to fulfill functions that are infeasible for automated vehicles alone due to technical or cost considerations. However, there is limited research on formulating and standardizing the intelligence levels of road infrastructure to facilitate the development, as the SAE automated driving levels have done for automated vehicles. This article proposes a five-level intelligence definition for intelligent roadway infrastructure, namely, connected and automated highway (CAH). The CAH is a subsystem of the more extensive collaborative automated driving system (CADS), along with the connected automated vehicle (CAV) subsystem. Leveraging the intelligence definition of CAH, the intelligence definition for the CADS is also defined. Examples of how the CAH at different levels operates with the CAV in the CADS are also introduced to demonstrate the dynamic allocation of various automated driving tasks between different entities in the CADS. 

Abstract From elementary particles to cosmological structures, topological solitons are ubiquitous nonlinear excitations valued for their robustness and complex interactions. In magnetism, solitons such as skyrmions and antiskyrmions behave analogously to particles and antiparticles, typically annihilating in pairs in accordance with topological conservation laws. Here the stripe‐to‐skyrmion transition is experimentally observed and a model for a skyrmion–antiskyrmion–skyrmion intertwined state is introduced, in which the central antiskyrmion is annihilated, leading to an increase in the local topological number. Because this transition occurs repeatedly across the film, the cumulative effect produces a global increase in the total topological charge. This model reflects a breakdown of topological protection in isotropic Dzyaloshinskii–Moriya interaction (DMI) materials, where symmetry constraints render the antiskyrmion energetically unstable and thermally activated. Using micromagnetic simulations and minimum‐energy‐path calculations, the antiskyrmion is identified as a transient, metastable excitation. To highlight its functional potential, this stripe‐to‐skyrmion transition within a Hall device is exploited to generate stochastic bitstreams, which are subsequently used in a proof‐of‐concept probabilistic computing demonstration. These results contribute to the understanding of topological spin‐texture dynamics and suggest opportunities for leveraging their transient behavior in probabilistic computing architectures. 

Abstract Studies of laser-driven strong field processes subjected to a (quasi-)static field have been mainly confined to theory. Here we provide an experimental realization by introducing a bichromatic approach for high harmonic generation (HHG) in a dielectric that combines an intense 70 femtosecond duration mid-infrared driving field with a weak 2 picosecond period terahertz (THz) dressing field. We address the physics underlying the THz field induced static symmetry breaking and its consequences on the efficient production/suppression of even-/odd-order harmonics, and demonstrate the ability to probe the HHG dynamics via the modulation of the harmonic distribution. Moreover, we report a delay-dependent even-order harmonic frequency shift that is proportional to the time derivative of the THz field. This suggests a limitation of the static symmetry breaking interpretation and implies that the resultant attosecond bursts are aperiodic, thus providing a frequency domain probe of attosecond transients while opening opportunities in precise attosecond pulse shaping.