We studied spin-dependent electronic and transport properties of silicon (Si)-doped armchair blue phosphorene nanoribbons (ABPNRs) via first-principles calculations combined with the non-equilibrium Green's function (NEGF) method, focusing on center-doped (SC) and edge-doped (SE) systems. Si doping induces prominent spin-polarized impurity sub-bands and endows pristine nonmagnetic semiconducting ABPNRs with magnetism, successfully converting them into magnetic semiconductors. Notably, the sub-bands of the center-doped nanoribbons exhibit stronger delocalization and lie closer to the Fermi level. Moreover, the transport results show that the SC system exhibits the most remarkable performance, featuring perfect bidirectional spin filtering, low-bias negative differential resistance, rectification, and giant magnetoresistance effects. The excellent spin-dependent transport behaviors can be explained by the transport spectra under different magnetic configurations, which basically depend on the symmetry matching of the electrode band structures. This reveals that the Si center-doped system has great potential for fabricating low-power, high-integration next-generation spintronic devices.

Solid-state quantum emitters (QEs) are central to quantum photonic technologies, but existing plasmonic and dielectric cavities rarely combine nanoscale spatial control, high photon flux, and polarization stability. We present a triangular gap-plasmon cavity integrated with monolayer WSe2 that achieves all three by coupling apex-concentrated strain fields with localized optical confinement, thereby realizing deterministic quantum light funneling to a sub-100 nm region. Finite-element simulations identify an optimal 66 nm geometry with a 20° apex angle, maximizing Purcell enhancement near 750 nm. Gold nanotriangles reproducibly activate three strain-induced QEs; the apex emitter exhibits g2 (0) = 0.054 (0.141 when coupled), a lifetime reduction from 16.8 to 0.248 ns (63-fold on average), and saturation counts up to 126 MHz into the first lens. Base emitters show a lower ∼23-fold enhancement, yielding a tip-to-base ratio of 2.7. Polarization studies across 41 QEs confirm dipole alignment within ±5°. When further combining this triangular platform with resonant excitation and tuning schemes, a scalable route toward indistinguishable single-photon sources on chip could be achieved.

The preparation and control of quantum states lie at the heart of quantum information science. Recent advances in solid-state quantum emitters (QEs) and nanophotonics have transformed the landscape of quantum photonic technologies, enabling scalable generation of quantum states of light and matter. A new frontier in solid-state quantum photonics is the engineering of many-body interactions between QEs and photons to achieve robust coherence and controllable many-body entanglement. These entangled states, including photonic graph and cluster states, superradiant emission and emergent quantum phases, are promising for quantum computation, sensing and simulation. However, intrinsic inhomogeneities and decoherence in solid-state platforms pose considerable challenges in realizing such complex entangled states. This Review provides an overview of fundamental many-body interactions and dynamics at the light–matter interfaces of solid-state QEs and discusses recent advances in mitigating decoherence and harnessing robust many-body coherence. Building scalable quantum technologies requires generating robust many-body entanglement in solid-state platforms. This Review highlights how engineered light–matter interactions, optical nonlinearities and coupling to nanophotonic structures enable coherent many-body entangled states that are resilient to disorder and decoherence.

We constructed S/Si-doped armchair blue phosphorene nanoribbons (aBPNRs) by selectively substituting the central (position "A") or edge (position "B") P atoms with S/Si atoms per unit cell, and further fabricated two p-n junction devices (D1 and D2) based on these doped nanoribbons. The electronic structures of doped aBPNRs and the spin-dependent transport properties of the devices were systematically investigated via first-principles calculations combined with nonequilibrium Green's function. The results show S-doped aBPNRs behave as non-magnetic metals (n-type), whereas Si-doped ones are magnetic semiconductors (p-type). Both D1 (center-doping) and D2 (edge-doping) devices exhibit excellent spin-dependent transport performances, including perfect spin filtering effect (nearly +/- 100% spin polarization in a wide bias range), significant rectification effect (maximum rectification rates of more than 106), and obvious negative differential resistance (NDR) behavior (peak-to-valley ratio exceeding 103 for spin-down current of D1). Moreover, our analysis reveals that the spin-up and spin-down currents can be unidirectionally filtered by adjusting the bias direction, endowing the devices with the capability to act as dual spin filters or diodes. Further analysis of transmission spectra and band structures reveals that these transport properties are essentially determined by the matching degree of energy bands between the left (S-doped) and right (Si-doped) electrodes as well as the distribution of transport peaks within the bias window. This work provides a theoretical basis for the design and application of high-performance aBPNRs-based spin electronic devices.

Two-dimensional (2D) intrinsic multiferroics have attracted considerable attention for the next generation of advanced information technologies. Herein, we report that bilayer Janus FeSCl, a novel 2D system designed by substituting sulfur in monolayer 1T-FeCl2, exhibits a giant spontaneous valley polarization and intrinsic magnetoelectric coupling. This Janus structure exhibits a ground-state bilayer structure that breaks space-inversion symmetry, enabling sliding ferroelectricity. Each monolayer displays robust intralayer ferromagnetic ordering, while the bilayer hosts interlayer antiferromagnetic alignment with opposing magnetic moments. Crucially, ferrovalley-mediated coupling links ferroelectric polarization and antiferromagnetic order, allowing electric-field-driven magnetic reversal. Notably, the direction of the net magnetic moment can be reversed through ferroelectric polarization switching, enabling nonvolatile control of the magnetism. The elucidated mechanisms are generalizable to diverse 2D material families, offering a universal framework for designing atomic-scale multiferroics. This work not only establishes foundational insights into 2D multiferroics but also advances the understanding of coupled charge-spin-valley physics in low-dimensional systems.

We employ non-equilibrium Green's function method and density functional theory to explore the electronic structure and transport properties of silicon-doped armchair blue phosphorene nanoribbons (ABPNRs). Band structure calculations reveal that silicon doping can induce a semiconductor-to-metal transition in ABPNRs. Devices based on these doped nanoribbons exhibit a pronounced negative differential resistance (NDR) effect. The peak biases of this effect can be efficiently controlled by the doping position and concentration. Compared with center-doped device (S1C), edge-doped device (S1E) has lower bias NDR effect. This can be explained by the molecular mechanism of the HOMO-LUMO gap and the spatial distribution of molecular projected self-consistent Hamiltonian (MPSH) eigenstates. Furthermore, as the doping concentration decreases, a notable shift in the peak bias of the NDR effect towards lower voltage domains is observed, with values even reaching the sub-millivolt or microvolt scale. This intriguing phenomenon can be attributed to the progressive narrowing of impurity bands within the left and right electrodes. Notably, at equivalent doping concentrations, the peak bias required to induce the NDR effect in Si-doped ABPNR devices is far lower than that reported for analogous devices based on graphene, hexagonal boron nitride or phosphorene nanoribbons. These findings highlight the promising potential of silicon-doped armchair blue phosphorene nanoribbons for the design of low-power nanoelectronic devices.

Interlayer excitons (IXs) in layered van der Waals materials are promising for quantum technologies and fundamental studies such as exciton-polariton condensation due to their large permanent dipole moments. However, their indirect bandgap optical transition through the Q-K channel renders them momentum forbidden and thus less relevant for optical applications. Here, we demonstrate a method for brightening momentum indirect Q-K transitions from IX quantum emitters (QEs) in 2H-stacked bilayer WSe2 by simultaneously employing local strain and plasmonic nanocavity coupling. Initially, long T1 lifetimes up to 140 ns are indicative of momentum indirect transitions. Magneto-photoluminescence data show a striking bimodal distribution of g-factors between mono- and bilayer QEs, with a well-defined value of g = 9.5 for IX, highlighting their momentum indirect nature and decoupling from local strain variations. In addition, angle-resolved PL measurements reveal that local curvature on the nanostressor induces a dipole orientation tilt of the QEs, affecting cavity coupling. By embedding these strained QEs into plasmonic cavities, we achieve a 10-fold increase in emission intensity and a 24-fold enhancement in the T1 lifetime in the best case (12-fold average), leading to bright single-photon emission rates up to 1.45 ± 0.1 MHz into the first lens. Moreover, the demonstrated brightening of IX transitions allowed to push the emission wavelength reliably to around 810 nm that enables free-space quantum optical communication.

The integration of 2D van der Waals (vdW) magnets with topological insulators or heavy metals holds great potential for realizing next-generation spintronic memory devices. However, achieving high-efficiency spin-orbit torque (SOT) switching of monolayer vdW magnets at room temperature poses a significant challenge, particularly without an external magnetic field. Here, it is shown field-free, deterministic, and nonvolatile SOT switching of perpendicular magnetization in the monolayer, diluted magnetic semiconductor (DMS), Fe-doped MoS2 (Fe:MoS2) at up to 380 K with a current density of approximate to 7 x 104 A cm-2. The in situ doping of Fe into monolayer MoS2 via chemical vapor deposition and the geometry-induced strain in the crystal break the rotational switching symmetry in Fe:MoS2, promoting field-free SOT switching by generating out-of-plane spins via spin-to-spin conversion. An apparent anomalous Hall effect (AHE) loop shift at a zero in-plane magnetic field verifies the existence of z spins in Fe:MoS2, inducing an antidamping-like torque that facilitates field-free SOT switching. This field-free SOT application using a 2D ferromagnetic monolayer provides a new pathway for developing highly power-efficient spintronic memory devices.

Based on single-molecule magnet Mn(dmit)2 and blue phosphorene nanoribbons, we construct a new molecular junction with different torsion angles between the molecule and electrodes. Applying nonequilibrium Green's function combined with density functional theory, we study the torsion effect on the spin-dependent electronic transport properties of the Mn(dmit)2 molecular junction. The obtained current-voltage curves reveal that three torsion configurations (M1, M2 and M3) of the molecular junction have excellent spin-filtering, spin-switching, and negative differential resistance effects. The interesting transport properties can be explained by the energy alignment of molecular projected self-consistent Hamiltonian (MPSH) eigenvalues, corresponding spatial distribution of MPSH eigenstate, local density of states (LDOS) at the Fermi level, and the bias-dependent transmission probability determined by the evolution of the transmission spectra. Moreover, the spin transport performance of the junction surpasses that of comparable junctions with Au, graphene nanoribbon, or phosphorene nanoribbon electrodes to some extent. Our results suggest that such torsion-tunable molecular junction could enable multifunctional spintronic applications, including high-efficiency spin filters, frequency multipliers, and ultrafast spin converters.

We design two p-n nanojunctions based on S- and Si- atoms doped armchair blue phosphorene nanoribbons (aBPNRs) including two semi-infinite electrodes and a scattering region and investigate their electronic and transport properties. Our calculations are based on density functional theory incorporated non-equilibrium Green's function approach. In impure aBPNRs, S/Si atoms substituted doping could greatly enhance the conductivity, and the S/Si doped aBPNRs show metallic properties. Based on the doped aBPNRs, devies D1 and D2 are constructed where the scattering region of D1 is formed by direct expansion of two electrodes, while the scattering region of D2 includes two undoped unit cells as buffer. The transport calculations show that both of D1 and D2 show excellent negative differential resistance (NDR) effect at low bias and significant rectification effects at high bias. Moreover, whether there is buffer in the scattering region has a great influence on the magnitude of current of the devices. Although the current of the device D1 without buffer is generally higher than that of the device D2, the NDR and rectification effects of D2 are better than D1 in terms of peak-to-valley ratio and rectification rate. These transport behaviors can be explained by the evolution of the transmission spectra, frontier molecular orbital and the symmetry matching between the band structures of the electrodes. This indicates that aBPNRs are a promising candidate for the future application of multi-functional electronic devices.

Chiral single photons are highly sought to enhance encoding capacities or enable propagation-dependent routing in nonreciprocal devices. Unfortunately, most semiconductor quantum emitters (QEs) produce only linear polarized photons unless external magnets are applied. Magnetic proximity coupling utilizing 2D ferromagnets promises to make bulky external fields obsolete. Here we directly grow Fe-doped MoS2 (Fe:MoS2) via chemical vapor deposition that displays pronounced hard ferromagnetic properties even in monolayer form. This approach with monolayer ferromagnets enables full utilization of the strain from the pillar stressor to form QE in WSe2 deterministically. The Fe:MoS2/WSe2 heterostructures display strong hysteretic magneto-response and high-purity chiral single photons with a circular polarization degree of 92 ± 1% (74% average) without external magnetic fields. Furthermore, the chiral single photons are robust against uncontrolled twist-angle and external stray-fields. This ability to manipulate quantum states and transform linear polarized photons into high-purity chiral photons on-chip enables nonreciprocal device integration in quantum photonics.

The recent discovery of strong spin Hall effects (SHEs) in two-dimensional layered topological semimetals has attracted intensive attention due to their exotic electronic properties and potential applications in spintronic devices. In this paper, we systematically study the topological properties and intrinsic SHEs of layered transition metal carbides M2C (M = V, Nb, Ta). The results show that d bands crossing near the Fermi level (EF) induce multiple nodal lines (NLs) and nodal points (NPs) in bulk and few-layered M2C, respectively. The inclusion of spin-orbit coupling breaks the degeneracy of NLs and NPs, contributing to large spin Hall conductivity (SHC) up to similar to 1100 and similar to 200 (h over bar /e)( cm)-1 for bulk and monolayer Ta2C, respectively. Remarkably, we find that the magnitude of SHC exhibits a significant enhancement by increasing the layer thickness. For eight-layer Ta2C, the maximum value of SHC can reach up to similar to 600 (h over bar /e)( cm)-1, comparable to many reported three-dimensional topological materials. Analysis of spin Berry curvature reveals that the large SHC originates from layer number dependent nodal-point structure near the EF, around where the repeated crossover between the valence and conduction bands creates large numbers of NPs in the -K and -M routes. Our findings not only provide a platform for experimental research of low-dimensional SHE, but also suggest an effective way of realizing giant SHE by controlling layer thickness.

Correction for 'First-principles prediction of two-dimensional MnOX (X = Cl, Br) monolayers: the half-metallic multiferroics with magnetoelastic coupling' by Yulin Feng, et al., Nanoscale, 2023, 15, 4546-4552, https://doi.org/10.1039/D2NR05764F.

Two-dimensional (2D) multiferroics have attracted extensive attention in recent years due to their potential applications in nano-electrical devices such as nonvolatile memory and magnetic sensors. However, 2D multiferroic materials with intrinsic ferromagnetism and ferroelasticity are very rare and most of them have low Curie temperatures. Herein, by performing the first-principles calculations, we systematically investigated the electronic structure and the magnetic properties of the MnOX (X = Cl, Br) monolayers. We demonstrated that the MnOX monolayers were intrinsic half-metallic multiferroics with the coexistence of ferromagnetism and ferroelasticity. The Curie temperatures evaluated from Monte Carlo simulations based on the Heisenberg model were about 220 K for MnOCl and 210 K for MnOBr, which could be further enhanced to 235 K and 230 K by 3% tensile strain. Moreover, their ground states exhibited significant big magnetic anisotropy energies of about 0.59 meV along the z-axis for MnOCl and 0.62 meV along the y-axis for MnOBr per unit cell. The in-plane magnetic easy axis of the MnOBr monolayer can be modulated by the ferroelastic switching due to the robust magnetoelastic coupling. These findings highlight that the MnOX monolayers (with 100% spin polarizability and high Curie temperature) are good candidates for next-generation multifunctional nanodevices.

Based on vanadium-doped zigzag phosphorene nanoribbon (ZPNRs), we investigate the electronic structures and spin-dependent transport properties by the first-principles calculations in combination with the nonequilibrium Green's function approach. We find that the ZPNRs can be tuned from nonmagnetic metals to magnetic metals or half-metals by different doping positions, which are caused by the hybridization among different electron orbitals under the crystal field. Moreover, a robust negative differential resistance effect is observed in all studied devices, and a perfect spin-filter effect with almost 100% spin polarization can be found under low bias. We analyze the transport properties in detail from the viewpoint of the transmission spectrum and molecular energy levels. These results indicate that the vanadium-doped ZPNRs have potential applications as multi-functional spintronic devices.

Light carries both spin angular momentum (SAM) and orbital angular momentum (OAM), which can be used as potential degrees of freedom for quantum information processing. Quantum emitters are ideal candidates towards on-chip control and manipulation of the full SAM–OAM state space. Here, we show coupling of a spin-polarized quantum emitter in a monolayer W S e 2 with the whispering gallery mode of a S i 3 N 4 ring resonator. The cavity mode carries a transverse SAM of σ = ± 1 in the evanescent regions, with the sign depending on the orbital power flow direction of the light. By tailoring the cavity–emitter interaction, we couple the intrinsic spin state of the quantum emitter to the SAM and propagation direction of the cavity mode, which leads to spin–orbit locking and subsequent chiral single-photon emission. Furthermore, by engineering how light is scattered from the WGM, we create a high-order Bessel beam which opens up the possibility to generate optical vortex carrying OAM states.

In this paper, we consider a crystal of molecular magnets interacting with four alternating magnetic fields. When a DC magnetic field applies to molecular magnets, the energy levels of molecular magnets can be recognized as a four-level system. We consider four wave mixing process in the crystal of molecular magnets, By solving the Schrödinger equation, the analytic solutions of the probe and mixing magnetic fields are obtained. We have also numerically investigated the dynamical evolution of the probe and mixing magnetic fields. The results show that probe and mixing filed periodically oscillate in the crystal of molecular magnets medium. By adjusting the frequency detuning and the intensity of the coupled magnetic fields, the storage and retrieval of microwave field can be achieved in molecular magnets. In the end, the second-order correlation function is calculated and the anti-bunching effect can be achieved in this magnetic medium.

van der Waals ferromagnets have gained significant interest due to their unique ability to provide magnetic response even at the level of a few monolayers. Particularly in combination with 2D semiconductors, such as the transition metal dichalcogenide WSe2, one can create heterostructures that feature unique magneto-optical response in the exciton emission through the magnetic proximity effect. Here we use 0D quantum emitters in WSe2 to probe for the ferromagnetic response in heterostructures with Fe(3)GT and Fe(5)GT ferromagnets through an all-optical read-out technique that does not require electrodes. The spectrally narrow spin-doublet of the WSe2 quantum emitters allowed to fully resolve the hysteretic magneto-response in the exciton emission, revealing the characteristic signature of both ferro- and antiferromagnetic proximity coupling that originates from the interplay among Fe(3)GT or Fe(5)GT, a thin surface oxide, and the spin doublets of the quantum emitters. Our work highlights the utility of 0D quantum emitters for probing interface magnetic dipoles in vdW heterostructures with high precision. The observed hysteretic magneto response in the exciton emission of quantum emitters adds further new degrees of freedom for spin and g-factor manipulation of quantum states.

By using first-principle calculations combined with the non-equilibrium Green's function approach, we studied the spin caloritronic properties of zigzag graphene nanoribbons with a nanobubble at the edge (NB-ZGNRs). The thermal spin-polarized currents can be induced by a temperature difference, and the spin Seebeck effect is found in the nanoribbon. The spin polarization, magnetoresistance, and Seebeck coefficients are discussed, which are strongly affected and can be tuned by the geometrical strain. Moreover, some novel spin caloritronic devices are designed, such as a device that generates bidirectional perfect spin currents and thermally induced giant magnetoresistances. Our results open up the possibility of tuning the spin caloritronic properties of the NB-ZGNR-based devices by changing the elastic strain on the graphene nanobubble.

为研究四能级单分子磁体中的电磁诱导透明现象,利用薛定谔方程,求解出概率幅运动方程,运用了微扰理论给出了单分子磁体系统对弱场响应的解析表达式,通过选取适当的参数,给出了概率幅方程的数值模拟结果,结果表明,当探测光与耦合光共振时,单分子磁体系统中会出现一个透明窗口,即电磁诱导透明现象.并分析了控制场强度和强场失谐量对透明窗口的影响.