- 标题
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Strong Coupling of a Single Photon to a Magnetic Vortex
摘要： Strong light-matter coupling means that cavity photons and other type of matter excitations are coherently exchanged. It is used to couple different qubits (matter) via a quantum bus (photons) or to communicate different type of excitations, e.g., transducing light into phonons or magnons. An unexplored, so far, interface is the coupling between light and topologically protected particle-like excitations as magnetic domain walls, skyrmions or vortices. Here, we show theoretically that a single photon living in a superconducting cavity can be strongly coupled to the gyrotropic mode of a magnetic vortex in a nanodisc. We combine numerical and analytical calculations for a superconducting coplanar waveguide resonator and different realizations of the nanodisc (materials and sizes). We show that, for enhancing the coupling, constrictions fabricated in the resonator are crucial, allowing to reach the strong coupling in CoFe discs of radius 200 ? 400 nm having resonance frequencies of few GHz. The strong coupling regime permits to coherently exchange a single photon and quanta of vortex gyration. Thus, our calculations show that the device proposed here serves as a transducer between photons and gyrating vortices, opening the way to complement superconducting qubits with topologically protected spin-excitations like vortices or skyrmions. We finish by discussing potential applications in quantum data processing based on the exploitation of the vortex as a short-wavelength magnon emitter.
关键词： cavity quantum electrodynamics,topological magnetism,coplanar waveguide resonators,nanoresonator,Magnetic vortex,light-matter interaction
更新于2025-09-23 15:19:57
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First principles study on the electronic and magnetic properties in Zn doped BiFe <sub/>0.9375</sub> Mg <sub/>0.0625</sub> O <sub/>3</sub> with intrinsic defects
摘要： Based on ?rst principles spin-polarized density functional theory plus U calculations, the electronic structure and magnetic properties of BiFe0.9375Mg0.0625O3 (BFMO) and Zn doped BiFe0.9375Mg0.0625O3 (BFMZO) are investigated. Compared with the BFMO, the magnetism of BFMZO is greatly enhanced and the calculated net magnetic moment of the supercell is 10.08 μB. The improved magnetic moment originates from the destroyed antiferromagnetic spin ordering of Fe3+–O–Fe3+ and the spin-polarized of O atoms. Electronic and magnetism of BFMZO with intrinsic defects (Bi and O vacancy) are also investigated. The existence of Bi vacancy favors the excitation of the Bi-6 s and O-2p impurity states into the band gap, in contrast, these in-gap impurities are passivated completely with the appearance of O vacancy in BFMZO. The defect of Bi vacancy imposes signi?cant in?uence on the electronic structure and magnetic behaviors, inducing a reduced net magnetic moment of about 7.98 μB, while the O vacancy almost has no effect on the magnetism of BMFZO. The improved ferromagnetism of Zn and Mg codoping suggesting a potential way to enhance the multiferroic properties of BiFeO3.
关键词： ?rst principles,magnetism,doping,BiFeO3
更新于2025-09-23 15:19:57
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Janus nanofiber array pellicle: facile conjugate electrospinning construction, structure and bifunctionality of enhanced green fluorescence and adjustable magnetism
摘要： A [Fe3O4/polyvinyl pyrrolidone (PVP)]//[Tb(BA)3phen/PVP] Janus nanofiber array pellicle (denoted JNAP) was successfully constructed by facile conjugate electrospinning without twisting for the first time. The JNAP offers the dual-functionality of fluorescence and magnetism. This technology entirely solves the dilemma of the magnetic spinning dope and fluorescent spinning dope being easily mixed together during the parallel electrospinning process, as it achieves complete segregation of magnetic nanoparticles and fluorescent molecules. Moreover, conjugate electrospinning without twisting has fewer requirements on the viscosity of the spinning dope compared with parallel electrospinning, in which the two spinning dopes should have the same viscosity. It was satisfactorily found that the JNAP has higher fluorescence intensity than the corresponding non-aligned Janus nanofiber pellicle. The magnetism of the JNAP could be tailored by changing the doping amount of the Fe3O4 NPs. The JNAP has potential applications in nanotechnology and biomedicine, etc., due to its enhanced green fluorescence and adjustable magnetism. In addition, this design concept and manufacturing process provide a facile way for preparing other one-dimensional Janus nanomaterials with multifunctionality.
关键词： magnetism,bifunctionality,conjugate electrospinning,fluorescence,Janus nanofiber
更新于2025-09-19 17:15:36
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Evaluation of the relationship between the magnetism and the optical properties in SrTiO3-δ defective systems: Experimental and theoretical studies
摘要： To explore the relationship between optical properties, oxygen vacancies and magnetism in SrTiO3, we prepared a series of SrTiO3-δ (δ=0.00, 0.125 and 0.250) samples by solid state reaction method followed by the creation of oxygen vacancies-δ. Surface composition and chemical valence state in the synthesized compounds were examined by X-ray photoelectron spectroscopy (XPS). The Fourier Transform Infrared spectroscopy (FT-IR) spectra showed that the transmission properties change with oxygen vacancies introduction. Ultraviolet-visible absorption revealed that optical properties were highly dependent on oxygen vacancies concentrations. When the magnetic field was applied, magnetization showed weak-ferromagnetism at room temperature on SrTiO3-δ non-sto?chiometric systems. Yet, it was reversed showing diamagnetism on SrTiO3 perfect crystal. The large concentration of oxygen vacancies (δ=0.250) reduced ferromagnetism and optical absorption, implying the possible presence of a relationship between the magnetism and the optical properties. Theoretical results showed two types of electronic contributions to magnetism, one of which emanates from localized states below the conduction band minimum, and the other comes from itinerant electrons of Ti atoms lying further away from the oxygen-vacancy. The electronic structures and magnetic properties were calculated by Full-Potential Linear Augmented Plane Wave (FP-LAPW) method within the Generalized Gradient Approximation (GGA) and the atomic relaxations introduced by the oxygen vacancies host in a fully self-consistent way. The results shed some light on the promising magneto-optical properties of the SrTiO3-δ materials.
关键词： Density Functional Theory (DFT),Optical properties,Oxygen vacancy,SrTiO3,Magnetism
更新于2025-09-19 17:15:36
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Imaging the local electronic and magnetic properties of intrinsically phase separated Rb<sub>x</sub>Fe<sub>2-y</sub>Se<sub>2</sub> superconductor using scanning microscopy techniques
摘要： The discovery in 2008 of the iron-based superconducting pnictide and chalcogenide compounds has provided an entirely new family of materials for studying the crucial interplay between superconductivity and magnetism in unconventional superconductors. The alkali-metal-intercalated iron selenide (AxFe2?ySe2, A = alkali metal) superconductors are of particular interest owing to their relatively high transition temperatures of 30 K and the co-existence of the superconducting state with antiferromagnetic ordering. Intrinsic phase separation on the mesoscopic scale is known to occur in “single crystals” of these compounds, adding to the complexity of interpretation of bulk property measurements. In this study, we investigate the local electronic structure and chemistry of RbxFe2?ySe2 crystals using scanning microscopy techniques. Nano-focussed angle-resolved photoemission spectroscopy (NanoARPES) has enabled the band structure of the minority superconducting phase and the non-superconducting matrix to be measured independently and linked to the surface chemistry from the same regions using core-level spectroscopy. Valence band mapping reveals the characteristic microstructure of these crystals, but does not have sufficient spatial resolution to enable the precise morphology of the superconducting phase to be elucidated. Cryogenic magnetic force microscopy (MFM) has shown that the superconducting phase has a fine-scale stripey morphology that was not resolved in the SPEM experiment. The correlation of these findings with previous microstructural studies, bulk measurements and first-principles DFT calculations paves the way for understanding the intriguing electronic and magnetic properties of these compounds.
关键词： RbxFe2?ySe2,phase separation,magnetism,superconductivity,scanning microscopy
更新于2025-09-19 17:15:36
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Enhanced photocatalytic ability and easy retrievable photocatalysts of Bi2WO6 quantum dots decorated magnetic carbon nano-onions
摘要： Bi2WO6 quantum dots (DQs) decorated magnetic carbon nano-onions (MCNOs) were prepared via a hydrothermal method. The Bi2WO6 QDs were measured to be about 2-10 nm and anchored on the surface of MCNOs uniformly. The great paramagnetic characteristic of composites was demonstrated by hysteresis loops measurement, and this feature made it easy to recover the photocatalysts from reaction system. In addition, rhodamine B (RhB), methylene blue (MB), and phenol were used to examine the photocatalytic performance of composites under visible light irradiation, and the reasons for the enhanced photocatalytic performance of composites compared with pure Bi2WO6 QDs were discussed by active trapping measurement and photocurrent response experiment. Results showed that MCNOs acted not only a magnetic supporter to prevent Bi2WO6 QDs from aggregation but also an electronic transmitter to decrease the recombination of photogenerated electron-hole (e--h+). The easy-retrievable photocatalysts with high photocatalytic performance will hold a great promise to be widely used in the field of water purification.
关键词： carbon nono-onions,magnetism,quantum dots,Bi2WO6
更新于2025-09-19 17:13:59
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Magnetism in monolayer InSe by nonmetal doping: First-principles study
摘要： To develop InSe-based spintronics devices, introducing magnetism into monolayer InSe is essential. In this work, the electronic and magnetic properties of nonmetal (NM) doped (H, B, C, Si, N, P, As, O, S, Te, F, Cl, Br and I) monolayer InSe were investigated by first-principles calculations. The results indicate that atoms from VA, VIA and VIIA groups are possible to substitute Se atoms under In-rich condition. Second, we have found that only the InSe doped with NM acceptors with odd number of valence electrons possesses magnetism. Especially B doped InSe is a half-metal. However, VIIA group doped InSe does not exhibit magnetism due to the In-In covalent bond. This work provides an important guidance for developing spintronic devices on monolayer InSe.
关键词： nonmetal doping,Monolayer InSe,magnetism,half-metal,In-In covalent bond
更新于2025-09-10 09:29:36
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Symmetry Modulation and Enhanced Multiferroic Characteristics in Bi <sub/>1-</sub><i> <sub/>x</sub></i> Nd <i> <sub/>x</sub></i> FeO <sub/>3</sub> Ceramics
摘要： BiFeO3 is recognized as the most important room temperature single phase multiferroic material. However, the weak magnetoelectric (ME) coupling remains as a key issue, which obstructs its applications. Since the magnetoelectric coupling in BiFeO3 is essentially hindered by the cycloidal spin structure, here efforts to improve the magnetoelectric coupling by destroying the cycloidal state and switching to the weak ferromagnetic state through symmetry modulation are reported. The structure is tuned from polar R3c to polar Pna2 1, and finally to nonpolar Pbnm by forming Bi1-xNdxFeO3 solid solutions, where two morphotropic phase boundaries (MPBs) are detected. Greatly enhanced ferroelectric polarization is obtained together with the desired weak ferromagnetic characteristics in Bi1-xNdxFeO3 ceramics at the compositions near MPBs. The change of magnetic state from antiferromagnetic (cycloidal state) to ferromagnetic (canted antiferromagnetic) is confirmed by the observation of magnetic domains using magnetic force microscopy. More interestingly, combining experiments and first-principles-based simulations, an electric field-induced structural and magnetic transition from Pna21 back to R3c is demonstrated, providing a great opportunity for electric field-controlled magnetism, and this transition is shown to be reversible with additional thermal treatment.
关键词： multiferroics,symmetry modulation,electric field-controlled magnetism,BiFeO3
更新于2025-09-10 09:29:36
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Homodinuclear {LnIII2} (LnIII = GdIII, TbIII, HoIII, and DyIII) Complexes: Field- Induced SMM Behavior of the DyIII and TbIII Analogues
摘要： A family of four dinuclear complexes, [NHEt3]2[Ln2(μ-NO3)2(NO3)2(HL)2] [Ln = GdIII (1), TbIII (2), HoIII (3), DyIII (4)], were synthesized by the reaction of an enolizable mutidentate Schiff base ligand H3L (H3L = N'-(2-hydroxy-3-methoxy-5-nitrobenzylidene)-2-(hydroxyimino)propanehydrazide) with hydrated lanthanide nitrates in the presence of NEt3. The molecular structure of complexes 1-4 was confirmed by single-crystal XRD analysis. All of the centrosymmetric complexes are dianionic, isostructural and each of the LnIII center is nine-coordinated and adopts a muffin like coordination geometry as indicated by SHAPE analysis. The dynamic magnetization studies revealed that the compounds 2 and 4 are field-induced single-molecule magnets with effective energy barriers, Ueff = 34(2) K (for 2) and 80(3) K (for 4) and pre-exponential factors, τo = 1.1 x 10-8 (for 2) and 1.15 x 10-7(for 4).
关键词： Tautomerism,Lanthanides,Schiff bases,Homodinuclear complexes,Magnetism
更新于2025-09-10 09:29:36
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The effects of point defects on the electronic and magnetic properties of GaN/ZnO heterojunction polar interface
摘要： The potential use of GaN/ZnO heterojunction as a magnetic material has been neglected because its magnetic properties are rarely studied. In this study, the magnetic properties of GaN/ZnO heterojunction interface are systematically calculated, and the effect of electric polarization intensity on the spin-electron was analyzed. Results showed that GaN/ZnO heterojunction interface exhibits a semiconducting feature. The magnetism of GaN/ZnO heterojunction interface is mainly affected by two factors. The first factor is the number of unpaired p-state electrons induced by cation vacancies, and the magnetism in the heterojunction interface originated from the spin polarization of these p-state electrons. The second factor is the electric polarization intensity in the heterojunction interface. If the electric polarization intensity is too low, then the unpaired p-electrons cannot be spin-polarized to produce a net magnetic moment. The spin polarization of p-state electrons increases with the increase in electric polarization intensity. Excessive electric polarization intensity inverts the spin direction of a part of p-state electrons, and ferromagnetic–ferrimagnetic–antiferromagnetic transition occurs in the heterojunction interface. Therefore, the magnetic property of GaN/ZnO heterojunction interface can be controlled by varying the electric polarization intensity.
关键词： First-principle,Magnetism,Point defects,GaN/ZnO heterojunction
更新于2025-09-10 09:29:36