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Strong Coupling of Magnons to Microwave Photons in Three-Dimensional Printed Resonators
摘要： We report on ferromagnetic resonant mode hybridization in re-entrant cavities made with a commercial three-dimensional (3D) printer, followed by conventional 3D metalization with copper and tin. The cavity volume was only 7% that of a standard cavity resonating at the same frequency, while maintaining a high quality factor. Simulations were in very good agreement. We obtained an effective coupling of about 40 MHz in two cavities at room temperature. These experimental results demonstrate the utility of tunable filters based on complex 3D printed cavities.
关键词： magnon photon polariton,3D Cavity spintronic,Yttrium Iron Garnet,3D printing,tunable filter
更新于2025-09-23 15:22:29
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Half-metallic ferromagnetic behavior in (Ga, Cr)N and (Ga, Cr, V)N compounds for spintronic technologies: Ab-initio and Monte Carlo methods
摘要： In this article, we investigate the magnetic- and electronic-proprieties of GaN doped with simple- and double-impurities utilizing Ab-initio and Monte Carlo studies. We have predicted that (Ga, Cr)N and (Ga, Cr, V)N compounds exhibit ferromagnetic- and halfmetallic-behavior with 100% spin-polarization at the Fermi-level. Moreover, we have found that Ga1-xCrxN and Ga1-2xCrxVxN (x = 0.04, 0.05 and 0.06) show a 2nd order ferromagnetic transition and that their Tc is above room temperature. These predictions make (Ga, Cr)N and (Ga, Cr, V)N compounds strong-candidates for spintronic-technologies.
关键词： Ab-initio calculations,Monte Carlo method,Diluted magnetic semiconductors,Spintronic,Gallium Nitride
更新于2025-09-23 15:22:29
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Observation of Optical Band-Gap Narrowing and Enhanced Magnetic Moment in Co-Doped Sol–Gel-Derived Anatase TiO <sub/>2</sub> Nanocrystals
摘要： The magnetic behavior of TiO2 and doped TiO2 nanocrystals has been a challenge due to the unambiguous nature of defects present in oxide semiconductors. Here, a simple, low-temperature sol?gel method is developed for the synthesis of low-dimensional and highly efficient stable anatase TiO2 nanocrystals. The X-ray powder diffraction pattern and Raman spectra confirm the formation of a single-phase anatase structure of TiO2. High-resolution transmission electron microscopy studies reveal the crystalline nature of the sol?gel-derived nanocrystals. The increase in lattice parameters together with the shifting and broadening of the most intense Eg(1) mode in micro-Raman spectra of Co-doped TiO2 nanocrystals indicate the incorporation of Co in TiO2. Shifting of the absorption edge to the visible region in UV?visible spectra indicates narrowing of the band gap due to Co incorporation in TiO2. X-ray photoelectron spectra confirm the presence of Co2+ and Co3+ in Co-doped TiO2 samples. Oxygen vacancy defects lead to the formation of bound magnetic polarons which induces a weak ferromagnetic behavior in air-annealed 3% Co-doped TiO2 at room temperature. It is observed that irrespective of the dopant ion, whether magnetic or nonmagnetic, the overlapping of bound magnetic polarons alone can induce ferromagnetism, while the magnetic impurities give rise to an enhanced paramagnetic moment for higher Co concentrations. A detailed understanding on the variation of these magnetic properties by estimating the concentration of bound magnetic polarons is presented, which is in corroboration with the photoluminescence studies. The observed band-gap narrowing in Co-doped TiO2 nanostructures and the mechanism underlying the magnetic interactions associated with the magnetic impurity concentration are advantageous from an applied perspective, especially in the field of spintronic and magneto-optic devices.
关键词： spintronic,magnetic moment,nanocrystals,optical band-gap narrowing,TiO2,magneto-optic devices,Co-doped,sol?gel
更新于2025-09-23 15:21:21
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Enhanced finite size and interface mixing effects in iridium manganese ultra thin films
摘要： The finite size and temperature dependent properties of antiferromagnets are of critical importance to a wide range of spintronic and neuromorphic computing devices. Here we present atomistic simulations of IrMn, one of the most technologically important antiferromagnets, in both the ordered (L12) and disordered (γ) phases. We have found that antiferromagnetic IrMn3 films show a stronger finite size dependence of the Néel temperature than an equivalent ferromagnet due to the existence of spin frustration. We also find that the disordered γ-IrMn3 phase shows a dramatic reduction in the Néel temperature to less than room temperature for films less than 1 nm thick. Interfacial intermixing of the IrMn3 with a non-magnetic Cu capping layer further reduces the Néel temperature for a given film thickness, with a stronger influence on the disordered γ-IrMn3 phase compared to the ordered L12-IrMn3 phase. Our results suggest a larger antiferromagnetic film thickness is required for devices operating at or above room temperature compared to an equivalent ferromagnet, particularly for sputtered films with a high degree of interfacial intermixing.
关键词： Néel temperature,antiferromagnets,neuromorphic computing,IrMn,spintronic devices,finite size effects
更新于2025-09-23 15:21:21
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Epitaxial Mn <sub/>5</sub> Ge <sub/>3</sub> (100) layer on Ge (100) substrates obtained by flash lamp annealing
摘要： Mn5Ge3 thin films have been demonstrated as promising spin-injector materials for germanium-based spintronic devices. So far, Mn5Ge3 has been grown epitaxially only on Ge (111) substrates. In this letter, we present the growth of epitaxial Mn5Ge3 films on Ge (100) substrates. The Mn5Ge3 film is synthetized via sub-second solid-state reaction between Mn and Ge upon flash lamp annealing for 20 ms at the ambient pressure. The single crystalline Mn5Ge3 is ferromagnetic with a Curie temperature of 283 K. Both the c-axis of hexagonal Mn5Ge3 and the magnetic easy axis are parallel to the Ge (100) surface. The millisecond-range flash epitaxy provides a new avenue for the fabrication of Ge-based spin-injectors fully compatible with CMOS technology.
关键词： epitaxial growth,spintronic devices,Ge (100) substrates,flash lamp annealing,Mn5Ge3
更新于2025-09-23 15:21:21
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Ultrafast dynamics in van der Waals heterostructures
摘要： Van der Waals heterostructures are synthetic quantum materials composed of stacks of atomically thin two-dimensional (2D) layers. Because the electrons in the atomically thin 2D layers are exposed to layer-to-layer coupling, the properties of van der Waals heterostructures are defined not only by the constituent monolayers, but also by the interactions between the layers. Many fascinating electrical, optical and magnetic properties have recently been reported in different types of van der Waals heterostructures. In this Review, we focus on unique excited-state dynamics in transition metal dichalcogenide (TMDC) heterostructures. TMDC monolayers are the most widely studied 2D semiconductors, featuring prominent exciton states and accessibility to the valley degree of freedom. Many TMDC heterostructures are characterized by a staggered band alignment. This band alignment has profound effects on the evolution of the excited states in heterostructures, including ultrafast charge transfer between the layers, the formation of interlayer excitons, and the existence of long-lived spin and valley polarization in resident carriers. Here we review recent experimental and theoretical efforts to elucidate electron dynamics in TMDC heterostructures, extending from timescales of femtoseconds to microseconds, and comment on the relevance of these effects for potential applications in optoelectronic, valleytronic and spintronic devices.
关键词： spin and valley polarization,charge transfer,valleytronic,transition metal dichalcogenide,Van der Waals heterostructures,excited-state dynamics,spintronic devices,interlayer excitons,optoelectronic
更新于2025-09-23 15:21:01
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Magnetic bipolar transistor based on ZnO/NiO/Si heterostructure using pulsed laser deposition
摘要： Oxide semiconductors are promising candidates for next generation electronics. In this work, magnetic bipolar transistor was fabricated by growing thin films of p-NiO and n-ZnO on n-type silicon wafer by pulsed laser deposition technique with an in-situ annealing at 670○ C in the presence of oxygen. The structural characterization of these films was done by X-ray diffraction and Raman spectroscopy and magnetic properties were studied by vibrating sample magnetometer (VSM). I-V characteristic of fabricated transistor was tested in common emitter configuration with DC biasing. Junction parameters such as ideality factor, series resistance, and transistor parameters like q-point were determined by using conventional transistor output characteristics. The diode and transistor showed an increase in current with the externally applied magnetic field due to the presence of Nickel or Oxygen vacancies in NiO attributing to spin polarized bipolar transport. Therefore the current amplification in these devices can be controlled by spin; making it attractive for spintronic applications.
关键词： oxide semiconductors,pulsed laser deposition,spintronic applications,magnetic bipolar transistor
更新于2025-09-23 15:19:57
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Remarkable negative differential resistance and perfect spin-filtering effects of the indium triphosphide (InP <sub/>3</sub> ) monolayer tuned by electric and optical ways
摘要： Fully spin-polarized current and negative differential resistance (NDR) are two important electronic transport properties for spintronic nanodevices based on two-dimensional materials. Here, we describe both the electric and optical tuning of the spin-polarized electronic transport properties of the indium triphosphide (InP3) monolayer, which is doped with Ge atoms, by using quantum transport calculations. The spin degeneration of the InP3 monolayer is lifted due to the doping of Ge atoms. By applying a small bias voltage, a fully spin-polarized current can be obtained along both the armchair and zigzag directions. Moreover, a remarkable NDR is observed for the current along the zigzag direction, which shows a huge peak-to-valley ratio of 3.1 (cid:2) 103, while in the armchair direction, a lower peak-to-valley ratio of 5.5 is obtained. Alternatively, a fully spin-polarized photocurrent can also be generated under the illumination of linearly-polarized light by tuning either the photon energy or the polarization angle.
关键词： spin-polarized current,negative differential resistance,InP3 monolayer,quantum transport calculations,Ge doping,spintronic nanodevices
更新于2025-09-23 15:19:57
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Half-metallic properties of transition metals adsorbed on WS2 monolayer: a first-principles study
摘要： Given the various applications of half-metals in the spintronics devises, we studied the structural, electronic and magnetic properties of transition-metal (TM) (Cr, Mn, Fe, Co, Ni, and Cu) adatoms on WS2 monolayer by performing first-principles calculations. Based on the adsorption energy, TM atoms prefer to occupy the TW site, above the W atoms, for all the cases. The results indicate that systems of Cr, Mn, Fe, and Co adsorbed on WS2 monolayer are magnetic, while in Ni and Cu atoms adsorbed don’t have any magnetic properties. The TM atoms are adsorbed chemically to the WS2 layer. The obtained values of the total magnetic moment vary from 4 μB to 1 μB in case of Cr to Co adsorption, respectively, which agree with the Slater–Pauling rule. Based on the magnetic moment of 0.00 μB, non-magnetic states are realized for Ni and Cu adsorption. More importantly, the high spin polarization of 100% at the Fermi level is achieved in the Cr, Mn, Fe and Co adsorption, which implies the potential for application in spintronic devices.
关键词： WS2,DFT,Spintronic,Half-metal,transition metal
更新于2025-09-19 17:15:36
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Characterizing the accelerating mode of a dielectric-lined waveguide designed for terahertz-driven manipulation of relativistic electron beams
摘要： We report on the generation of a terahertz (THz) beam with a quasi-TEM01 mode by exploiting the interferometric recombination of two linearly polarized emitters in a combined spintronic source. The generated THz beam was used to characterize the accelerating mode of a dielectric-lined waveguide (DLW) to inform on the recent demonstration of relativistic electron beam manipulation achieved with this THz-driven DLW at the CLARA research facility at Daresbury Laboratory.
关键词： dielectric-lined waveguide,relativistic electron beams,spintronic source,quasi-TEM01 mode,terahertz
更新于2025-09-16 10:30:52