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Bei Sun

Publications and source records attributed to Bei Sun.

3 recordsLinked to original sources

STRIDE: A Self-Reflective Agent Framework for Reliable Automatic Equation Discovery

LLM-based equation discovery offers a promising route to recovering symbolic laws from data, but many systems still rely on generation-centered loops that propose candidates, fit parameters, score results, and reuse selected examples. Such loops can misjudge useful skeletons under unreliable fitting, discard near-correct equations that require repair, and accumulate redundant memories that provide limited guidance. We propose STRIDE, a self-reflective agent framework that improves reliability by coordinating data-aware generation, mixed-fitting evaluation, critic--executor repair, and diversity-preserving semantic memory. By turning fitted scores and candidate behavior into shared feedback, STRIDE enables equations to be proposed, assessed, refined, and reused within a closed-loop discovery process. Experiments on representative symbolic-regression benchmarks and LSR-Synth suites show that STRIDE improves accuracy, OOD robustness, and structural recovery across multiple LLM backbones, with ablations and analyses confirming the contribution of its core components.

cs.AI

Magnetic-field switching of exciton-magnon coupling in LiNiPO$_4$

Exciton-magnon transitions provide a fundamental optical fingerprint of coupled excitonic and magnetic excitations in antiferromagnets. However, controlling such coupled excitations by external fields remains a key challenge. Here we report the temperature and magnetic-field evolution of exciton-magnon coupling in the magnetoelectric antiferromagnet LiNiPO$_4$ using pulsed magnetic fields up to 50 T. The magnon sideband intensity exhibits sharp switching across field-induced magnetic phases, with strong suppression in plateau phases and enhancement in canted spin states. This behavior is attributed to the interplay between the thermal magnon population and the spin-dependent optical transition matrix element. These results demonstrate that magnetic-field control of spin degrees of freedom enables selective switching of exciton-magnon coupling in antiferromagnets.

cond-mat.str-el

Miniaturized and robust tunable monochromatic magneto-optical platform for pulsed magnetic fields

Tunable monochromatic magneto-transmission is one of the most established magneto-optical techniques, particularly well suited for pulsed magnetic fields. It employs fixed-wavelength monochromatic light as the probe, while the magnetic field is swept to bring the sample into resonance with the photon energy. The key component of this setup is a tunable laser system, typically consisting of a Ti:sapphire laser coupled with an optical parametric oscillator. However, such laser systems are often bulky, expensive, and inherently unstable, which significantly limits their widespread application in magneto-optical laboratories. In this work, we develop a high-accuracy, cost-effective, and compact tunable monochromatic magneto-transmission system based on a combination of a laser-driven white light source and a mini monochromator, and demonstrate its feasibility and performance in a millisecond-range pulsed magnetic field condition. To verify the accuracy of this new and simplified setup, we performed Faraday rotation measurements on the geometrically frustrated spin system CdCr2O4, as well as magneto-transmission experiments on the Shastry-Sutherland lattice antiferromagnet SrCu2(BO3)2. These results show excellent agreement with previous reports, confirming the reliability and precision of the new setup.

cond-mat.str-el