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Zhouqi Li

Publications and source records attributed to Zhouqi Li.

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Topology-Biased Resource Constraints Shape Synchronization Pathways in Hindmarsh-Rose Oscillator Networks

In oscillator networks sustained by finite resources, synchronization can depend on both the total resource and its spatial distribution. We study a duplex system whose activity layer consists of chaotic Hindmarsh--Rose oscillators and whose transport layer redistributes a conserved resource through a degree-biased Markov process. The stationary resource field is characterized analytically, and its existence, uniqueness, and convergence are established. By embedding this field into a local adaptive feedback law, the available resource is converted into node-dependent dissipation, for which Lyapunov analysis guarantees convergence to the synchronization manifold. Numerical results show that topology bias reorganizes the transient route to synchronization. Weak bias produces an almost collective contraction, whereas intermediate bias creates a hub-initiated recruitment hierarchy that extends toward middle-degree and peripheral nodes. Under stronger bias, the degree hierarchy becomes more pronounced while peripheral recruitment slows because adaptive dissipation is concentrated on structurally privileged nodes. Across the explored parameter range, this localization--coverage tradeoff is accompanied by a non-monotonic synchronization response at fixed total resource. The largest Lyapunov exponent remains positive after synchronization and the correlation dimension changes only modestly, consistent with suppression of transverse deviations while chaotic motion is retained on the synchronization manifold.

nlin.AO

Itinerant antiferromagnetism in the antagonistic pair compound Y$_4$Co$_3$Ag

Low dimensional crystallographic motifs have long been associated with desirable physical properties. The confinement of electrons to low dimensions is thought to enhance quantum fluctuations and may promote correlated phenomena. Here, using the antagonistic pair concept, we add Y to the immiscible Co-Ag pair to discover Y$_4$Co$_3$Ag. This compound adopts a monoclinic $I$2/$m$ structure consisting of Y channels that are filled by one-dimensional zigzag and hexagonal Co chains, which extend along the crystallographic $b$-axis with no nearest neighbor contacts between Co and Ag atoms. Transport, magnetic, and specific heat measurements reveal that Y$_4$Co$_3$Ag orders antiferromagnetically at $T_N=14.9$ K with an effective magnetic moment $\mu_{\text{eff}}$ = 1.4 $\mu_{\text{B}}$/Co. Specific heat measurements show only a small entropy loss on the order of $0.1\,R\ln2$ associated with magnetic order, and magnetization isotherms, in DC fields up to 70 kOe at 1.8 K and in pulsed fields up to 600 kOe at 500 mK, indicate a small ordered moment of less than 0.2 $\mu_B$/Co. Taken together, our results imply the presence of small, itinerant moments and strong fluctuations in Y$_4$Co$_3$Ag, suggesting that Y$_4$Co$_3$Ag may be a promising candidate material to investigate itinerant magnetic interactions in a quasi-one dimensional system.

cond-mat.str-el