arXiv subjects

Tianci Gong

Publications and source records attributed to Tianci Gong.

4 recordsLinked to original sources

arXiv2026

Rotational Doppler Effect and Helimagnon Frequency Comb in Sliding Magnetic Spirals

Collective spin motion can reshape magnon spectra by providing a dynamical magnetic background. Magnetic spirals offer a particularly clean setting, as they simultaneously host propagating helimagnons and a gapless Goldstone mode, i.e., the sliding of the spiral. Here, we show that once a helimagnon is excited and the spiral slides, the motion, which rotates the local spin frame, produces a thresholdless rotational Doppler shift of the helimagnon spectrum, with even winding for the linear mode and odd winding for its second harmonic. Stronger excitation generates one finite-momentum phason. Mixing of that phason with the helimagnon produces a helimagnon frequency comb only inside a finite driving window, spaced by the phason frequency fixed by the spiral length rather than by the sliding rate. These two scales are separable in a microwave experiment: the Doppler offset tracks the sliding velocity, whereas the comb spacing scales inversely with the length of the spiral.

cond-mat.mtrl-sci↗

arXiv2026

Stimulated Magnonic Frequency Combs

Magnonic frequency combs, characterized by a series of discrete frequency lines, have emerged as a promising frontier in magnon spintronics, with potential applications in advanced information processing and sensing technologies. Although the three-magnon scattering process is widely recognized as a fundamental mechanism for generating these combs, its experimental realization has remained challenging due to the high threshold power and strict conservation of momentum and energy. In this work, we propose a novel mechanism for the stimulated generation of magnonic frequency combs that overcomes these limitations. Our approach offers precise and efficient control over key comb properties, including spacing between spectral lines and the number of lines, marking a significant advancement in the field. We substantiate this mechanism through a robust combination of theoretical modeling, micromagnetic simulations, and experimental validation. This study not only demonstrates the feasibility of our method but also opens new pathways for integrating magnonic frequency combs into practical spintronic devices.

cond-mat.mes-hall↗

arXiv2025

Interaction-Driven Altermagnetic Magnon Chiral Splitting

Nonrelativistic magnon chiral splitting in altermagnets has garnered significant recent attention. In this work, we demonstrate that nonlinear three-wave mixing -- where magnons split or coalesce -- extends this phenomenon into unprecedented relativistic regimes. Employing a bilayer antiferromagnet with Dzyaloshinskii-Moriya interactions, we identify three distinct classes of chiral splitting, each dictated by specific symmetries, such as $C_4T$, $σ_v T$, or their combination. This reveals a novel bosonic mechanism for symmetry-protected chiral splitting, capitalizing on the unique ability of magnons to violate particle-number conservation, a feature absent in low-energy fermionic systems. Our findings pave the way for engineering altermagnetic splitting, with potential applications in advanced magnonic devices and deeper insights into magnon dynamics in complex magnetic systems.

cond-mat.mtrl-sci↗

arXiv2025

Strong coupling of chiral magnons in altermagnets

Altermagnets recently are identified as a new class of magnets that break the time-reversal symmetry without exhibiting net magnetization. The role of the dipole-dipole interaction (DDI) on their dynamical properties however is yet to be addressed. In this work, we show that the DDI can induce the strong coupling between exchange magnons with opposite chiralities in altermagnets, manifesting as a significant level repulsion in the magnon spectrum. Crucially, the predicted magnon-magnon coupling is highly anisotropic, and observable in practical experiments. These exotic features are absent in conventional antiferromagnets. Our findings open a new pathway for quantum magnonic information processing based on altermagnetism.

cond-mat.mtrl-sci↗