arXiv subjects

Huanfeng Zhu

Publications and source records attributed to Huanfeng Zhu.

6 recordsLinked to original sources

arXiv2024

Optical Routing via High Efficiency Composite Acoustic Diffraction

Acousto-optical modulation (AOM) is a powerful and widely used technique for rapidly controlling the frequency, phase, intensity, and direction of light. Based on Bragg diffraction, AOMs typically exhibit moderate diffraction efficiency, often less than 90\% even for collimated inputs. In this work, we demonstrate that this efficiency can be significantly improved using a composite (CP) setup comprising a pair of 4-F-linked AOMs, enabling beamsplitting with fully tunable splitting amplitude and phase. The efficiency enhancement arises from two effects, termed "momentum echo" and "high-order rephasing," which can be simultaneously optimized by adjusting the relative distance between the two AOMs. This method is resource-efficient, does not require ultra-collimation, and maintains control bandwidth. Experimentally, we achieved a diffraction efficiency exceeding 99\% (excluding insertion loss) and a 35 dB single-mode suppression of the 0th-order beam, demonstrating a full-contrast optical router with a switching time of less than 100~nanoseconds. Theoretically, we formulate the dynamics of CP-AOM in terms of multi-mode quantum control and discuss extensions beyond the $N=2$ configuration presented in this work. The substantially enhanced performance of CP-AOMs, coupled with reduced acoustic amplitude requirements, may significantly advance our ability to accurately control light at high speeds with low-loss acousto-optics.

physics.optics↗

arXiv2023

Third order nonlinear transport properties in topological chiral antiferromagnetic semimetal CoNb3S6

The topology between Bloch states in reciprocal space has attracted tremendous attention in recent years. The quantum geometry of the band structure is composed of quantum metric as real part and berry curvature as imaginary part. While the Berry curvature, the Berry curvature dipole and Berry connection polarizability have been recently revealed by the first order anomalous hall, second order and third order nonlinear Hall effect respectively, the quantum metric induced second order nonlinear transverse and longitudinal response in topological antiferromagnetic material MnBi2Te4 was only very recently reported. Here we demonstrate the similar third order nonlinear transport properties in the topological antiferromagnetic CoNb3S6. We observed that the third order nonlinear longitudinal V3ω xx increase significantly at the antiferromagnetic transition temperature TN ~ 29 K, which was probably induced by the quantum metric without time-reversal symmetry or inversion symmetry. Besides, temperature-dependent nonlinear behaviour was observed in the first order I-V curve below the Neel temperature TN, which was not reported in MnBi2Te4 and FeSn. Such nonlinear I-V behaviour hints for the possible existence of Charge Density Wave (CDW) state, which has been discovered in its sister material FeNb3S6. Simultaneously, two plateaus in the third order nonlinear longitudinal V3ω xx~ I^ω curve are observed, which is also speculated to be related with the possible CDW state. However, the genuine mechanism for the first order nonlinear I-V and its relation with the third order nonlinear transport call for more experimental investigations and theoretical interpretation. Our work provides a way to explore third harmonic nonlinear transport and interaction with magnetic order and CDW.

cond-mat.mtrl-sci↗

arXiv2023

The Influence of Dimensionality on the Charge Density Wave Transition and Its Application on Mid-infrared Photodetection

Two-dimensional charge density wave (CDW) materials received much attention for high responsivity and broadband photodetection in recent years, due to their collective electron transport and narrow bandgap. However, the high dark current density problem hinders their real application. Here we report a sharp CDW transition in quasi-1D (TaSe4)2I, and apply it for broadband photodetection. Especially at mid-infrared region, the device shows both high photo responsivity of 1.18e3 A/W and large light on-off ratio of 80, which is superior than 2D CDW TaS2 and most reported low-dimensional materials. The fact for such high performance lies on two aspects. One is the much lower dark current density resulted from the pseudo gap associated with 1D Luttinger liquid state, which is supported by finite size scaling of nonlinear I-V at variable temperatures and occurrence of 1D structural phase transition consolidated by In-situ Raman spectroscopy. The other is the high photocurrent associated with the Frohlich superconductivity state, manifested by an ultrasensitive switching, which can be only accessible in 1D CDW materials, in agreement with our density functional theory calculation. Our work thus reveals the pivotal role of dimensionality in CDW phase transition, and paves a way for implementing highly sensitive broadband photodetector.

cond-mat.mtrl-sci↗

arXiv2023

Fast Fabrication of WS2/Bi2Se3 Heterostructures for High Performance Photodetection

Two-dimensional (2D) material heterostructures have attracted considerable attention owing to their interesting and novel physical properties, which expand the possibilities for future optoelectronic, photovoltaic, and nanoelectronic applications. A portable, fast, and deterministic transfer technique is highly needed for the fabrication of heterostructures. Herein, we report a fast half wet poly(dimethylsiloxane) (PDMS) transfer process utilizing the change of adhesion energy with the help of micron-sized water droplets. Using this method, a vertical stacking of the WS2/Bi2Se3 heterostructure with a straddling band configuration is successfully assembled on a fluorophlogopite substrate. Thanks to the complementary band gaps and high efficiency of interfacial charge transfer, the photodetector based on the heterostructure exhibits a superior responsivity of 109.9 A/W for a visible incident light at 473 nm and 26.7 A/W for a 1064 nm near-infrared illumination. Such high photoresponsivity of the heterostructure demonstrates that our transfer method not only owns time efficiency but also ensures high quality of the heterointerface. Our study may open new pathways to the fast and massive fabrication of various vertical 2D heterostructures for applications in twistronics/valleytronics and other band engineering devices.

cond-mat.mes-hall↗

arXiv2023

A simplified method characterizing magnetic ordering modulated photo-thermoelectric response in noncentrosymmetric semimetal Ca3Ru2O7

Photo-Thermoelectric (PTE) response is usually one of the main working mechanisms for photodetectors. However, as another fast and easier way to measure thermoelectric characteristics of materials, it can also reveal important physics such as electric-phonon coupling, electron-electron correlation, etc. Recently, the spin entropy related to magnetic order transition which contributes to thermoelectric power is attracting more and more attention. Here, we demonstrate the PTE response can be reshaped when Ca3Ru2O7 undergoes meta-magnetic phase (MMP) transition driven by both temperature and magnetic field. Firstly, a sign change is observed crossing TS = 48 K and the linear polarization angle dependent PTE current maximizes along a-axis above TS while maximizes along b-axis below TS, which indicates that the antiferromagnetic spin order contributes to such spatial anisotropy. Secondly, in the temperature range of around 40 ~ 50 K, the PTE current is found to be sharply suppressed when external magnetic field is applied in plane along a-axis but is only gradually suppressed when applied field is along b-axis which gives out two critical fields. We attribute such suppression of PTE current under magnetic field to the suppression of the spin entropy in the phase transition between the antiferromagnetic state and the MMP state and the H-T phase diagrams of Ca3Ru2O7 is redrawn accordingly. Compared to previously work which trying to understand the magnetic phase transition in Ca3Ru2O7, such as neutron scattering, specific heat, and other advanced transport measurements, our work provides a more convenient yet efficient method, which may also find applications in other correlated spin materials in general.

cond-mat.str-el↗

arXiv2023

Highly tunable lateral homojunction formed in 2D layered CuInP2S6 via in-plane ionic migration

As basic building blocks for next-generation information technologies devices, high-quality p-n junctions based on van der Waals (vdW) materials have attracted widespread interest.Compared to traditional two dimensional (2D) heterojunction diodes, the emerging homojunctions are more attractive owing to their intrinsic advantages, such as continuous band alignments and smaller carrier trapping. Here, utilizing the long-range migration of Cu + ions under in-plane electric field, a novel lateral p-n homojunction was constructed in the 2D layered copper indium thiophosphate (CIPS). The symmetric Au/CIPS/Au devices demonstrate an electric-field-driven resistance switching (RS) accompanying by a rectification behavior without any gate control. Moreover, such rectification behavior can be continuously modulated by poling voltage. We deduce that the reversable rectifying RS behavior is governed by the effective lateral build-in potential and the change of the interfacial barrier during the poling process. Furthermore, the CIPS p-n homojuction is evidenced by the photovoltaic effect, with the spectral response extending up to visible region due to the better photogenerated carrier separation efficiency. Our study provides a facile route to fabricate homojuctions through electric-field-driven ionic migration and paves the way towards the use of this method in other vdW materials.

cond-mat.mes-hall↗