arXiv subjects

Longji Cui

Publications and source records attributed to Longji Cui.

6 recordsLinked to original sources

arXiv2026

Inductance Meets Memory in the Quantum Magnet Mn3Si2Te6

Orbital degrees of freedom offer a largely untapped route to emergent dynamical phenomena in correlated quantum materials. However, it remains unclear whether collective orbital states can intrinsically generate both reactive and memory functionalities in a bulk system. Here we show that in the ferrimagnet Mn3Si2Te6, nonequilibrium reconfiguration of chiral orbital currents produces both emergent inductance and nonvolatile memristance as intrinsic properties of a single crystal. At low frequency and under a magnetic field along the c axis, coherent orbital-current domains generate robust clockwise inductive I-V loops. At higher frequency and low field, current-driven first-order reconfiguration leads to incomplete reversal and metastable trapping, producing an intrinsic electromotive force and a finite remanent voltage at zero current. These results establish orbital currents as a class of quantum state variables that encode both reactive and memory functionalities, opening routes toward intrinsically reconfigurable and energy-efficient electronic systems.

cond-mat.str-el↗

arXiv2025

On-chip Single-crystal Plasmonic Optoelectronics for Efficient Hot Carrier Collection and Photovoltage Detection

Large-area chemically synthesized single-crystal metals with nanometer-scale thickness have emerged as promising materials for on-chip nanophotonic applications, owing to their superior plasmonic properties compared to nanofabricated polycrystalline counterparts. While much recent attention has focused on their optical properties, the combined optimal electrical and optical characteristics, which hold great potential for high-performance optoelectronic functionalities, remain largely unexplored. Here, we present a single-crystal plasmonic optoelectronic platform based on nanowires fabricated from synthesized gold flakes and demonstrate its capabilities for highly enhanced hot carrier collection, electroluminescence, and photovoltage detection. Notably, single-crystal gold nanogap devices exhibit an order of magnitude higher open-circuit photovoltage compared to polycrystalline devices, representing one of the highest reported photovoltage sensing performances in terms of on-chip device density and responsivity per area. Our analysis revealed that this enhancement is attributed mostly to the suppression of electron-phonon scattering and improved hot carrier tunneling efficiency in single-crystal devices. These results highlight the potential of large-scale single-crystal nanostructures for both fundamental studies of nanoscale hot carrier transport and scalable electrically driven nanophotonic applications.

physics.optics↗

arXiv2022

Tuning light emission crossovers in atomic-scale aluminum plasmonic tunnel junctions

Atomic sized plasmonic tunnel junctions are of fundamental interest, with great promise as the smallest on-chip light sources in various optoelectronic applications. Several mechanisms of light emission in electrically driven plasmonic tunnel junctions have been proposed, from single-electron or higher order multi-electron inelastic tunneling to recombination from a steady-state population of hot carriers. By progressively altering the tunneling conductance of an aluminum junction, we tune the dominant light emission mechanism through these possibilities for the first time, finding quantitative agreement with theory in each regime. Improved plasmonic resonances in the energy range of interest increase photon yields by two orders of magnitude. These results demonstrate that the dominant emission mechanism is set by a combination of tunneling rate, hot carrier relaxation timescales, and junction plasmonic properties.

cond-mat.mes-hall↗

arXiv2021

Thousand-fold Increase in Plasmonic Light Emission via Combined Electronic and Optical Excitations

Surface plasmon enhanced processes and hot-carrier dynamics in plasmonic nanostructures are of great fundamental interest to reveal light-matter interactions at the nanoscale. Using plasmonic tunnel junctions as a platform supporting both electrically- and optically excited localized surface plasmons, we report a much greater (over 1000x) plasmonic light emission at upconverted photon energies under combined electro-optical excitation, compared with electrical or optical excitation separately. Two mechanisms compatible with the form of the observed spectra are interactions of plasmon-induced hot carriers and electronic anti-Stokes Raman scattering. Our measurement results are in excellent agreement with a theoretical model combining electro-optical generation of hot carriers through non-radiative plasmon excitation and hot-carrier relaxation. We also discuss the challenge of distinguishing relative contributions of hot carrier emission and the anti-Stokes electronic Raman process. This observed increase in above-threshold emission in plasmonic systems may open avenues in on-chip nanophotonic switching and hot carrier photocatalysis.

physics.optics↗

arXiv2019

Electrically Driven Hot-Carrier Generation and Above-threshold Light Emission in Plasmonic Tunnel Junctions

Above-threshold light emission from plasmonic tunnel junctions, when emitted photons have energies significantly higher than the energy scale of the incident electrons, has attracted much recent interest in nano-optics, while the underlying physical mechanism remains elusive. We examine above-threshold light emission in electromigrated tunnel junctions. Our measurements over a large ensemble of devices demonstrate a giant material dependence of photon yield (emitted photons per incident electrons), as large as four orders of magnitude. This dramatic effect cannot be explained only by the radiative field enhancement effect due to the localized plasmons in the tunneling gap. Emission is well described by a Boltzmann spectrum with an effective temperature exceeding 2000 K, coupled to a plasmon-modified photonic density of states. The effective temperature is approximately linear in the applied bias, consistent with a suggested theoretical model in which hot carriers are generated by non-radiative decay of electrically excited localized plasmons. Electrically driven hot-carrier generation and the associated non-traditional light emission could open new possibilities for active photochemistry, optoelectronics and quantum optics.

cond-mat.mes-hall↗

arXiv2012

Ultrafast modulation of near-field heat transfer with tunable metamaterials

We propose a mechanism of active near-field heat transfer modulation relying on externally tunable metamaterials. A large modulation effect is observed and can be explained by the coupling of surface modes, which is dramatically varied in the presence of controllable magnetoelectric coupling in metamaterials. We finally discuss how a practical picosecond-scale thermal modulator can be made. This modulator allows manipulating nanoscale heat flux in an ultrafast and noncontact (by optical means) manner.

cond-mat.mes-hall↗