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Y. L. Zhang

Publications and source records attributed to Y. L. Zhang.

12 recordsLinked to original sources
arXiv2026

An input-output approach for giant atom scatterings beyond the dipole approximation

A giant atom is an artificial matter configuration whose spatial scale is comparable to the wavelength of the interacting electromagnetic wave, such that the usual electric-dipole approximation is no longer valid. As a consequence, certain quasi-direct scattering channels for the electromagnetic wave can arise. Given that the well-known input-output approach can only work for the usual point scattering configuration, wherein the electric-dipole approximation is well satisfied, here we develop a modified input-output approach, wherein an additional low-Q cavity channel is introduced, to treat the electromagnetic scattering problem of a giant atom. We demonstrate that, beyond the multiple coupling-point model used widely in recent publications, the present approach can well explain the Fano-type scattering spectra observed generically and extract certain physical parameters, including the energy dissipation parameter of a two-level giant atom and its coupling strength with the scattered electromagnetic wave. Consequently, we argue that various high-performance optical quantum devices, typically the giant-atom-based optical quantum switches, can be generated by engineering the Fano-type scatterings of giant atoms.

quant-ph↗
arXiv2025

Pressure-induced structural and superconducting transitions in black arsenic

We report high-pressure Raman spectra and resistance measurements of black arsenic (b-As) up to 58 GPa, along with phonon density of states (DOS) and enthalpy calculations for four reported arsenic phases up to 50 GPa. It is found that metastable b-As transforms into gray arsenic (g-As) phase at a critical pressure of 1.51 GPa, followed by subsequent transitions to simple cubic arsenic (c-As) and incommensurate host-guest arsenic (hg-As) phases at 25.9 and 44.8 GPa, respectively. Superconductivity emerges above 25 GPa in the c-As phase, with the superconducting transition temperature ($T$$\rm_c$) remaining nearly a constant of 3 K. Upon further compression, $T$$\rm_c$ steeply increases to a higher value around 4.5 K in the incommensurate hg-As phase above 43 GPa. We use our results to update the structural and superconducting phase diagrams under pressure for the novel semiconductor, black arsenic.

cond-mat.supr-con↗
arXiv2018

Staggered field driven domain walls motion in antiferromagnetic heterojunctions

In this work, we study the antiferromagnetic (AFM) spin dynamics in heterostructures which consist of two kinds of AFM layers. Our micromagnetic simulations demonstrate that the AFM domain-wall (DW) can be driven by the other one (driven by field-like Neel spin-orbit torque, Phys. Rev. Lett. 117, 017202 (2016)) through the interface couplings. Furthermore, the two DWs detach from each other when the torque increases above a critical value. The critical field and the highest possible velocity of the DW depending on several factors are revealed and discussed. Bases on the calculated results, we propose a method to modulate efficiently the multi DWs in antiferromagnet, which definitely provides useful information for future AFM spintronics device design.

physics.app-ph↗
arXiv2018

Microwave fields driven domain wall motions in antiferromagnetic nanowires

In this work, we study the microwave field driven antiferromagnetic domain wall motion in an antiferromagnetic nanowire, using the numerical calculations based on a classical Heisenberg spin model. We show that a proper combination of a static magnetic field plus an oscillating field perpendicular to the nanowire axis is sufficient to drive the domain wall propagation along the nanowire with the axial magnetic anisotropy. More importantly, the drift velocity at the resonance frequency is comparable to that induced by temperature gradients, suggesting that microwave field can be a very promising tool to control domain wall motions in antiferromagnetic nanostructures. Furthermore, the dependences of resonance frequency and drift velocity on the static and oscillating fields, the axial anisotropy, and the damping constant are discussed in details. This work provides useful information for the spin dynamics in antiferromagnetic nanostructures for spintronics applications.

physics.app-ph↗
arXiv2017

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE

The DArk Matter Particle Explorer (DAMPE), also known as Wukong in China, launched on December 17, 2015, is a new high energy cosmic ray and γ-ray satellite-borne observatory in space. One of the main scientific goals of DAMPE is to observe GeV-TeV high energy γ-rays with accurate energy, angular, and time resolution, to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays, it is challenging to identify γ-rays with sufficiently high efficiency minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations, using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at $\sim10$ GeV amounts to less than 1% of the selected sample. Finally, we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.

physics.ins-det↗
arXiv2017

Spatial resolution measurement of Triple-GEM detector and diffraction imaging test at synchrotron radiation

A triple-GEM detector with two-dimensional readout is developed. The detector provides high position resolution for powder diffraction experiments at synchrotron radiation. Spatial resolution of the detector is measured in the lab using a 55Fe X-ray source. A resolution of about 110 um FWHM is achieved. The energy resolution is better than 27% for 5.9 keV X-rays. The detector's validity under illumination of photons in particular energy range is verified using a Cu X-ray tube. Imaging of the head of a wire stripper with X-ray tube demonstrates its imaging ability. A diffraction imaging experiment using the sample of powder SiO2 is successfully carried out at 1W2B laboratory of Beijing Synchrotron Radiation Facility (BSRF). Different diffraction rings are clearly seen under various X-ray energies.

physics.ins-det↗
arXiv2016

Thermal stimulated current response in cupric oxide single crystal thin films over a wide temperature range

Cupric oxide single crystal thin films were grown by plasma-assisted molecular beam epitaxy. X-ray diffraction, Raman spectrum and in situ reflection high-energy electron diffraction show that the thin films are 2x2 reconstructed with an in-plane compression and out-of-plane stretching. Thermal stimulated current measurement indicates that the electric polarization response presents in the special 2D cupric oxide single crystal thin film over a wide temperature range from 130 K to near-room temperature. We infer that the abnormal electric response involves the changing of phase transition temperature induced by structure distortion, the spin frustration and magnetic fluctuation effect of short-range magnetic order, or the combined action of both two factors mentioned above. This work suggests a promising clue for finding new room temperature single phase multiferroics or tuning phase transition temperature.

cond-mat.mtrl-sci↗
arXiv2015

Isobaric yield ratio difference between the 140 $A$ MeV $^{58, 64}$Ni + $^{9}$Be reactions studied by antisymmetric molecular dynamics model

\item[Background] The isobaric yield ratio difference (IBD) method is found to be sensitive to the density difference of neutron-rich nucleus induced reaction around the Fermi energy. \item[Purpose] An investigation is performed to study the IBD results in the transport model. \item[Methods] The antisymmetric molecular dynamics (AMD) model plus the sequential decay model GEMINI are adopted to simulate the 140$A$ MeV $^{58, 64}$Ni + $^{9}$Be reactions. A relative small coalescence radius R$_c =$ 2.5 fm is used for the phase space at $t =$ 500 fm/c to form the hot fragment. Two limitations on the impact parameter ($b1 = 0 - 2$ fm and $b2 = 0 - 9$ fm) are used to study the effect of central collisions in IBD. \item[Results] The isobaric yield ratios (IYRs) for the large--$A$ fragments are found to be suppressed in the symmetric reaction. The IBD results for fragments with neutron-excess $I = $ 0 and 1 are obtained. A small difference is found in the IBDs with the $b1$ and $b2$ limitations in the AMD simulated reactions. The IBD with $b1$ and $b2$ are quite similar in the AMD + GEMINI simulated reactions. \item[Conclusions] The IBDs for the $I =$ 0 and 1 chains are mainly determined by the central collisions, which reflects the nuclear density in the core region of the reaction system. The increasing part of the IBD distribution is found due to the difference between the densities in the peripheral collisions of the reactions. The sequential decay process influences the IBD results. The AMD + GEMINI simulation can better reproduce the experimental IBDs than the AMD simulation.

nucl-ex↗
arXiv2015

Two successive magneto-structural transformations and their relation to enhanced magnetocaloric effect for Ni55.3Mn19.7Ga25 Heusler alloy

In the present work, two successive magneto-structural transformations (MSTs) consisting of martensitic and intermartensitic transitions have been reported in polycrystalline Ni55.8Mn18.1Ga26.1 Heusler alloy. Benefiting from the additional latent heat contributed from intermediate phase, this alloy exhibits a large transition entropy change ΔStr with the value of ~28 J/kg K. Moreover, the magnetocaloric effect (MCE) has been also evaluated in terms of Maxwell relation. For the magnetic field change of 3 T, it is found that the calculated value of refrigeration capacity for Ni55.8Mn18.1Ga26.1 attains to ~72 J/kg around room temperature, which significantly surpasses those obtained in many Ni-Mn based Heusler alloys. The mechanism underlying the enhanced MCE is believed to be responsible for these multiple transformations, which can sustain the pronounced isothermal entropy change ΔST over a relatively wide temperature interval.

cond-mat.mtrl-sci↗
arXiv2013

The study of neutron activation yields in spallation reaction of 400 MeV/u carbon on a thick lead target

The spallation-neutron yield was studied experimentally by bombarding a thick lead target with 400 MeV/u carbon beam. The data were obtained with the activation analysis method using foils of Au, Mn, Al, Fe and In. The yields of produced isotopes were deduced by analyzing the measured γ spectra of irradiated foils. According to the isotopes yields, the spatial and energy distributions of the neutron field were discussed. The experimental results were compared with Monte Carlo simulations performed by the GEANT4 + FLUKA code.

nucl-ex↗
arXiv2005

Optical properties of $MgCNi_3$ in the normal state

We present the optical reflectance and conductivity spectra for non-oxide antiperovskite superconductor $MgCNi_{3}$ at different temperatures. The reflectance drops gradually over a large energy scale up to 33,000 cm$^{-1}$, with the presence of several wiggles. The reflectance has slight temperature dependence at low frequency but becomes temperature independent at high frequency. The optical conductivity shows a Drude response at low frequencies and four broad absorption features in the frequency range from 600 $cm^{-1}$ to 33,000 $cm^{-1}$. We illustrate that those features can be well understood from the intra- and interband transitions between different components of Ni 3d bands which are hybridized with C 2p bands. There is a good agreement between our experimental data and the first-principle band structure calculations.

cond-mat.supr-con↗