arXiv subjects

Hongye Zhang

Publications and source records attributed to Hongye Zhang.

4 recordsLinked to original sources

arXiv2026

Multiband-Induced Complex Magnetotransport in the Kagome Metal LuNb$_6$Sn$_6$

We report the electrical transport properties of the kagome metal LuNb$_6$Sn$_6$, which undergoes a charge density wave (CDW) transition at $T_\mathrm{CDW}\approx80$ K. Similar to the kagome metals $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs), LuNb$_6$Sn$_6$ develops complex magnetotransport behavior near and below the CDW transition. In particular, the longitudinal magnetoconductivity exhibits an approximately linear field dependence below about 1 T, whereas the field dependence of Hall conductivity displays pronounced nonlinearity and a field-induced sign reversal. Although an anomalous Hall-like contribution can be extracted by subtracting a local background from the Hall conductivity, mobility-spectrum analysis shows that the overall magnetotransport can be largely accounted for by multiband conduction involving high-mobility electronlike and holelike carriers. Nevertheless, sizable deviations from the multiband model emerge near $T_{\mathrm{CDW}}$, pointing to additional CDW-related scattering processes. These results demonstrate that high-mobility multiband transport, together with CDW-induced modifications of carrier scattering, play important roles in the complex magnetotransport of LuNb$_6$Sn$_6$.

cond-mat.str-el↗

arXiv2026

Hybridization-Induced Enhancement of the Thermoelectric Response in the Kagome Material CsCr$_6$Sb$_6$

Flat bands in kagome lattices provide a prominent route to strongly correlated electronic states. Here we report charge and thermal transport measurements on single crystals of CsCr$_6$Sb$_6$, a kagome Kondo system arising from the hybridization between flat and dispersive bands. The Seebeck coefficient and Nernst signal increase rapidly below $T_\mathrm{F}\sim70$ K, concomitant with the emergence of short-range antiferromagnetic correlations and flat-band resonance. The Nernst coefficient in the intermediate-temperature range of $\sim30-80$ K further follows the universal scaling reported for prototypical heavy-fermion compounds, consistent with the development of strongly renormalized quasiparticles associated with hybridization. Both the Seebeck and Nernst responses reach extrema at a lower temperature $T_\mathrm{p}\sim20-25$ K, where phonon drag and correlated quasiparticles may both contribute. These results reveal a hybridization-induced enhancement of the thermoelectric response and establish CsCr$_6$Sb$_6$ as a kagome platform for probing flat-band-derived Kondo physics through thermoelectric transport.

cond-mat.str-el↗

arXiv2024

Optimisation and Loss Analyses of Pulsed Field Magnetisation in a Superconducting Motor with Cryocooled Iron Cores

A 2D electromagnetic-thermal coupled numerical model has been developed using the finite element method and validated against experimental data to investigate a superconducting machine featuring high-temperature superconducting (HTS) tape stacks and cryocooled iron cores. The HTS stacks are transformed into trapped field stacks (TFSs) through pulsed field magnetisation (PFM), generating rotor fields. After PFM, the superconducting motor operates on the same principle as permanent magnet synchronous motors. This study explores the behaviour of HTS stacks by altering the stack's layer number from one to nine and adjusting the pulsed current amplitude from 250 A to 1000 A. The primary objective of this paper is to identify the optimal combination of pulsed current amplitudes and TFS layer numbers for achieving maximum magnetisation fields. The secondary objective is to evaluate the overall losses in both superconducting and non-superconducting parts of the machine during magnetisation, including heat generated in various layers of the TFS, and losses in the motor's active materials (copper windings and iron cores). Two motor configurations were proposed, and two calculation methods using linear interpolation of iron losses and steel grades were introduced to estimate the iron losses for the studied iron material, M270-35A. This pioneering study is expected to serve as a valuable reference for loss analyses and structural design considerations in developing superconducting machines.

cond-mat.supr-con↗

arXiv2020

VELC: A New Variational AutoEncoder Based Model for Time Series Anomaly Detection

Anomaly detection is a classical but worthwhile problem, and many deep learning-based anomaly detection algorithms have been proposed, which can usually achieve better detection results than traditional methods. In view of reconstruct ability of the model and the calculation of anomaly score, this paper proposes a time series anomaly detection method based on Variational AutoEncoder model(VAE) with re-Encoder and Latent Constraint network(VELC). In order to modify reconstruct ability of the model to prevent it from reconstructing abnormal samples well, we add a constraint network in the latent space of the VAE to force it generate new latent variables that are similar with that of training samples. To be able to calculate anomaly score in two feature spaces, we train a re-encoder to transform the generated data to a new latent space. For better handling the time series, we use the LSTM as the encoder and decoder part of the VAE framework. Experimental results of several benchmarks show that our method outperforms state-of-the-art anomaly detection methods.

cs.LG↗