arXiv subjects

Jiguang Yao

Publications and source records attributed to Jiguang Yao.

7 recordsLinked to original sources

arXiv2026

Theory and Experiment of Chirality-induced Magnetic Nonreciprocity Manifested by Coupling Phase

Magnetic interactions have long served as the most robust and widely used approach for realizing nonreciprocity, with an externally applied magnetic field breaking time-reversal symmetry (TRS) and chiral photon-magnon interactions introducing spatial asymmetry. In this work, we investigate the chirality mechanisms essential for magnetic nonreciprocity from a unified experimental and theoretical perspective. We begin by examining conventional chiral interactions that generate chiral electromagnetic fields through specially designed structures, and then place particular emphasis on synthetic chirality enabled by nontrivial phase accumulation in traveling-wave-mediated coupling systems. We establish a microscopic theoretical framework that maps field polarization onto the phase of a complex coupling strength and validate it with systematic experiments, thereby providing a consistent formalism that describes both conventional and synthetic chirality. Notably, we highlight the symmetry properties and the unique features of synthetic chirality that distinguish it from conventional nonreciprocal mechanisms.

cond-mat.mes-hall↗

arXiv2026

Coherent perfect absorption of anti-modes in an indirect coupled magnon-polariton system

In this work, we report coherent perfect absorption (CPA) of anti-modes in an indirectly coupled magnon--polariton system. By examining both single and indirectly coupled cases, we experimentally distinguish the modal decay rate $γ$ from the effective decay rate $γ_{\rm{eff}}$. At CPA, $γ_{\rm{eff}} = 0$, leading to a vanishing output and a visually narrow spectrum in the dB-scale, while the intrinsic linewidth set by $2γ$ remains unchanged, demonstrating that the effective decay rate dictates the spectral amplitude rather than the physical loss. Furthermore, in the indirectly coupled system, CPA persists over a broad, magnetically tunable detuning range, in contrast to the single-detuning CPA observed in the directly coupled case, thereby enabling magnetically reconfigurable and frequency-selective microwave absorbers.

cond-mat.mes-hall↗

arXiv2025

Nonreciprocal Control of the Speed of Light Using Cavity Magnonics

We demonstrate nonreciprocal control of the speed of light by sending a microwave pulse through a cavity magnonics device. In contrast to reciprocal group velocity controlled by conventional electromagnetically induced transparency (EIT) effect, incorporating dissipative magnon-photon coupling establishes a non-reciprocal EIT effect, allowing slow and fast light propagation in opposite directions at the same frequency with comparable amplitude. Remarkably, reversing the magnetic field enables a directional switch between non-reciprocal fast and slow light. This discovery may offer new possibilities for pulse time regulation in microwave signal communications, neuromorphic computing, and quantum signal processing.

physics.optics↗

arXiv2024

Anomalous Long-Distance Coherence in Critically-Driven Cavity Magnonics

Developing quantum networks necessitates coherently connecting distant systems via remote strong coupling. Here, we demonstrate long-distance coherence in cavity magnonics operating in the linear regime. By locally setting the cavity near critical coupling with travelling photons, non-local magnon-photon coherence is established via strong coupling over a 2-meter distance. We observe two anomalies in this long-distance coherence: first, the coupling strength oscillates twice the period of conventional photon-mediated couplings; second, clear mode splitting is observed within the cavity linewidth. Both effects cannot be explained by conventional coupled-mode theory, which reveal the tip of an iceberg of photon-mediated coupling in systems under critical driving. Our work shows the potential of using critical phenomena for harnessing long-distance coherence in distributed systems.

quant-ph↗

arXiv2023

Thickness and temperature dependent damping in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ epitaxial films

The damping of La0.67Sr0.33MnO3 (LSMO) epitaxial films as a function of thickness at different temperatures was studied. The competition between two scattering types (\r{ho}-like and σ-like) with entirely distinct thickness and temperature dependencies resulted in complicated damping behavior. The behavior of σ-like damping in LSMO films is consistent with the behavior in magnetic metal films. However, because \r{ho}-like damping is sensitive to the fine electron structure near the Fermi surface, the distortion of the oxygen octahedra controlled by the film thickness is an important factor in controlling the damping. Our study demonstrates that the complexity of damping in LSMO epitaxial films is a consequence of strong-correlation effects, which are characteristic of complex transition-metal oxides.

cond-mat.mtrl-sci↗

arXiv2022

Giant spin ensembles in waveguide magnonics

The dipole approximation is usually employed to describe light-matter interactions under ordinary conditions. With the development of artificial atomic systems, `giant atom' physics is possible, where the scale of atoms is comparable to or even greater than the wavelength of the light they interact with, and the dipole approximation is no longer valid. It reveals interesting physics impossible in small atoms and may offer useful applications. Here, we experimentally demonstrate the giant spin ensemble (GSE), where a ferromagnetic spin ensemble interacts twice with the meandering waveguide, and the coupling strength between them can be continuously tuned from finite (coupled) to zero (decoupled) by varying the frequency. In the nested configuration, we investigate the collective behavior of two GSEs and find extraordinary phenomena that cannot be observed in conventional systems. Our experiment offers a new platform for `giant atom' physics.

quant-ph↗

arXiv2020

Observation of spin-orbit magnetoresistance in CoFeB/heavy metal/MgO with existence of both spin Hall effect and Edelstein effect

In this paper, we report the observation of spin-orbit magnetoresistance (SOMR) in ferromagnetic metal/heavy metal/MgO system. We measure the magnetoresistance as the function of the thickness of heavy metal (HM) for CoFeB/HM/MgO and CoFeB/HM films where HM = Pt and Ta. Besides the conventional spin Hall magnetoresistance (SMR) peak, the evidence of the SOMR is indicated by another peak of the MR ratio when the thickness of HM is around 1 ~ 2 nm for CoFeB/HM/MgO films, which is absent for CoFeB/HM films. We speculate the SOMR observed in our experiment originates from the spin-orbit coupling at the HM/MgO interface. We give the boundary conditions of our samples and calculate the theoretical magnetoresistance based on spin diffusion equation. Based on the theoretical results, we can explain the two peaks we observe separately comes from the spin current generated by spin Hall effect and by Edelstein effect.

cond-mat.mes-hall↗