arXiv subjects

Huidong Li

Publications and source records attributed to Huidong Li.

4 recordsLinked to original sources

arXiv2026

Electrical manipulation of oxygen stoichiometry in multiterminal YBa$_2$Cu$_3$O$_{7-\delta}$ junctions

Local manipulation of oxygen stoichiometry offers a route to control the electronic properties of complex oxides, yet the selective modification of individual current-carrying branches through oxygen redistribution remains unexplored in multiterminal high-temperature superconducting junctions. In a YBa$_2$Cu$_3$O$_{7-\delta}$ Y-shaped three-terminal device, we demonstrate the possibility to electrically control oxygen vacancy migration on a hand-picked terminal while largely preserving the other two. Oxygen-depleted propagating fronts are directly visualized by the resulting change in optical reflectivity and they are linked to the evolution of the electrical response. The process is highly directional and determined by the polarity of the applied current, allowing for the creation of either a converging or a diverging propagating front from the central node of the Y-shaped device. The associated changes in resistance exhibit relaxation on a timescale of minutes, driven by the vacancy concentration gradient. Effects of oxygen migration are also mapped by Kelvin Probe Force Microscopy and Scanning Laser Microscopy, which probe work-function changes and spatially resolved variations in the superconducting transition, respectively. Notably, the Tc contrast revealed by the latter provides a quantitative handle on the underlying oxygen content, enabling direct visualization of oxygen redistribution. Finite-element modeling and nanoprobe X-ray diffraction qualitatively reproduce the observed vacancy redistribution. These results establish a post-fabrication route to locally tune properties of superconducting multiterminal devices such as nanocryotrons, yTron, and tunable weak links.

cond-mat.supr-con↗

arXiv2026

Effect of pulse duration on current-induced selective oxygen migration in high-Tc superconductors

High current densities can induce the directional diffusion of atoms in metallic films. In YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO), this electromigration process selectively acts on oxygen atoms lying in the Cu-O chains, permitting to vary the oxygen concentration in a targeted spot of high current density. This approach has proven successful in mapping the phase diagram of the material as a function of carrier concentration or as a way to manufacture memristive devices owing to its reversibility under small bipolar excitations. Thus far, most of the investigations have been limited to pulsed excitation with current/voltage pulses on a millisecond or longer scale, for which thermal effects undeniably influence the process. In the present work, we explore the impact of pulse length $\delta t$ on the onset current of electromigration, $I_{\text{EM}}$, of YBCO bridges, covering the range from 200 ns to 1 ms. As $\delta t$ decreases below $\sim 10~\mu$s, $I_{\text{EM}}$ exhibits a rapid increase. Analytical and numerical estimates of the local temperature show that as pulses shorten, the temperature decreases, making the electromigration process more athermal. These findings are relevant for the operation of memristors and should be taken into account when describing the effects of thermomagnetic instabilities in thin films.

cond-mat.supr-con↗

arXiv2025

Magnetotransport signatures of spin-orbit coupling in high-temperature cuprate superconductors

Spin transport in superconductors offers a compelling platform to merge the dissipationless nature of superconductivity with the functional promise of spin-based electronics. A significant challenge in achieving spin polarisation in conventional superconductors stems from the singlet state of Cooper pairs, which exhibit no net spin. The generation of spin-polarised carriers, quasiparticles, or triplet pairs in superconductors has predominantly been realised in hybrid superconductor/ferromagnet systems through proximity-induced spin polarisation. Historically, cuprate superconductors have been characterised by strong electronic correlations but negligible spin-orbit coupling. Here, we report exceptionally large anisotropic magnetoresistance and a pronounced planar Hall effect arising near the superconducting phase transition in the prototypical high-temperature cuprate superconductor YBa2Cu3O7-x without using a proximity ferromagnet. These effects, unprecedented in centrosymmetric cuprates, emerge from spin-polarised quasiparticle transport mediated by strong spin-orbit coupling. By systematically tuning magnetic field strength, orientation, temperature, and doping, we show clear evidence of spin-orbit-driven transport phenomena in a material class long thought to lack such interactions. Our findings reveal an unexpected spin-orbit landscape in cuprates and open a route to engineer spintronic functionalities in high-temperature superconductors.

cond-mat.mes-hall↗

arXiv2024

A wideband amplifying and filtering reconfigurable intelligent surface for wireless relay

Programmable metasurfaces have garnered significant attention due to their exceptional ability to manipulate electromagnetic (EM) waves in real time, leading to the emergence of a prominent area in wireless communication, namely reconfigurable intelligent surfaces (RISs), to control the signal propagation and coverage. However, the existing RISs usually suffer from limited operating distance and band interference, which hinder their practical applications in wireless relay and communication systems. To overcome the limitations, we propose an amplifying and filtering RIS (AF-RIS) to enhance the in-band signal energy and filter the out-of-band signal of the incident EM waves, ensuring the miniaturization of the RIS array and enabling its anti-interference ability. In addition, each AF-RIS element is equipped with a 2-bit phase control capability, further endowing the entire array with great beamforming performance. An elaborately designed 4*8 AF-RIS array is presented by integrating the power dividing and combining networks, which substantially reduces the number of amplifiers and filters, thereby reducing the hardware costs and power consumption. Experimental results showcase the powerful capabilities of AF-RIS in beam-steering, frequency selectivity, and signal amplification. Therefore, the proposed AF-RIS holds significant promise for critical applications in wireless relay systems by offering an efficient solution to improve frequency selectivity, enhance signal coverage, and reduce hardware size.

eess.SP↗