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First-principles investigation on the interlayer doping of SnSe2 bilayer
摘要： Using density functional theory calculations, we systematically investigated the effects of numbers and types of transition metals (TM) on the magnetic property of SnSe2 bilayer nanosheet. Our results revealed that, when one TM is introduced into the interlayer, the magnetic moment induced by the Co and Ni is tiny while it is largely strengthened with the doping of V, Cr, Mn, and Fe. When two TMs are inserted into the interlayer, Vand Cr make the system change into a weak antiferromagnetism (AFM) state while Mn-, Fe-, Co-doped systems display a weak ferromagnetism (FM) ground state. These FM states have the magnetic moments which double those of the one TM–doping systems. With the TM numbers further increasing to four, the robust AFM and FM features appear with the doping of Fe and Mn, respectively. Ni cannot induce any magnetism whatever the numbers of Ni are filling in. Interestingly, with the increase of the numbers of dopants, transitions from FM to AFM and AFM to FM are predicted to be realized on Fe-SnSe2 and Cr-SnSe2 systems, respectively. This kind of transition may be important for the applications in spintronic devices.
关键词： Interlayer doping,Spintronics application,Density functional theory,Antiferromagnetism,Modeling and simulation,Ferromagnetism,SnSe2
更新于2025-09-10 09:29:36
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Tuning spin-charge interconversion with quantum confinement in ultrathin bismuth films
摘要： Spin-charge interconversion (SCI) phenomena have attracted a growing interest in the field of spintronics as a means to detect spin currents or manipulate the magnetization of ferromagnets. The key ingredients to exploit these assets are a large conversion efficiency, the scalability down to the nanometer scale, and the integrability with optoelectronic and spintronic devices. Here, we show that, when an ultrathin Bi film is epitaxially grown on a Ge(111) substrate, quantum size effects arising in nanometric Bi islands drastically boost the SCI efficiency, even at room temperature. Using x-ray diffraction, scanning tunneling microscopy, and spin- and angle-resolved photoemission, we obtain a clear picture of the film morphology, crystal, and electronic structures. We then directly probe SCI with three different techniques: magneto-optical Kerr effect to detect the charge-to-spin conversion generated by the Rashba-Edelstein effect (REE), optical spin orientation, and spin pumping to generate spin currents and measure the spin-to-charge conversion generated by the inverse Rashba-Edelstein effect (IREE). The three techniques show a sizable SCI only for 1–3-nm-thick Bi films corresponding to the presence of bismuth nanocrystals at the surface of germanium. Due to three-dimensional quantum confinement, those nanocrystals exhibit a highly resistive volume separating metallic surfaces where SCI takes place by (I)REE. As the film size increases, the Bi film becomes continuous and semimetallic leading to the cancellation of SCIs occurring at opposite surfaces, resulting in an average SCI that progressively decreases and disappears. These results pave the way for the exploitation of quantum size effects in spintronics.
关键词： Rashba-Edelstein effect,bismuth films,spintronics,quantum size effects,Spin-charge interconversion
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - N Anoscale Magnetometry Using Single Spin Quantum Sensors
摘要： Advancing the frontiers of nanoscience and information technology hinges on the availability of novel tools for nanoscale sensing and imaging. Solid-state electronic spins offer a unique platform to implement high-performance quantum sensing devices, which address this need and go beyond what classical technologies offer. We present a robust technology to realise this concept, which is based on nano-engineered diamond devices, hosting single electronic spins for sensing. We will describe the key principles underlying these novel quantum sensors and discuss some of their areas of applications which we have opened over the last years. These include the field of antiferromagnetic spintronics, where single spin magnetometry already yields unprecedented insight into domain formation and non-trivial spin-textures in antiferromagnets. Next to these room-temperature applications, we will present results of cryogenic single spin magnetometry for quantitative, high resolution imaging of vortices and supercurrents in nanoscale superconductors. These examples illustrate the remarkable performance that single spin quantum sensing offers, and which holds great promise for future applications in various applicatons of the nano-sciences.
关键词： scanning probe,spintronics,antiferromagnets,single spins,uncertainty,measurement techniques,Quantum sensing,precision measurements
更新于2025-09-10 09:29:36
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Current-Induced Spin Polarization in Nonmagnetic Semiconductors
摘要： The use of spontaneous electron spin polarization in nonmagnetic semiconductors avoids the transport challenges of electron spin injection from magnetic materials as well as packing constraints of small magnets in a dense array. Although the focus of rearch on the spontaneous spin polarization of electrical current has been on spin-orbit fields and their effects, in principle a moving electron gas can be unstable to forming spin-polarized distributions via carrier scattering processes that are independent of the carrier spin. The two required elements for such current-induced spin polarization without spin-orbit interactions are (1) the presence of built-in spatially-varying electric fields, either naturally forming (as in the Gunn effect) or extrinsic (as in a junction with spatially dependent doping) and (2) energy-dependent carrier scattering processes. As spin-orbit interactions are not required for this effect, it should occur in inversion-symmetric materials like silicon that lack zero-field spin splittings and materials like zinc oxide and gallium nitride that lack significant spin-orbit interactions.
关键词： Spin-orbit fields,Current-induced spin polarization,Spintronics
更新于2025-09-10 09:29:36
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Reference Module in Materials Science and Materials Engineering || III-V and Group-IV-Based Ferromagnetic Semiconductors for Spintronics
摘要： From the first development of the transistor, the rapid growth of solid-state electronic circuits has been quite impressive. Innovations of semiconductor (SC) processing technologies have helped keep the pace of developing smaller electronic devices with higher performance. Operations of most electronic devices rely on the ability to control the flow of charges. However, when electronic devices reach the scale of 10 nm or even smaller, two big problems appear. First, many kinds of fluctuation make it difficult to control the flow of electron charges. For example, when the channel length of field effect transistors (FETs) reaches several nanometers, the transport of electrons cannot be described by the conventional diffusion equation. In nanoscale devices, even fluctuation of positions of doped atoms strongly affects the movement of electrons, making it difficult to predict and control the output current. This results in large fluctuation of device parameters. The second problem is the leak off-current that results in the large idling energy dissipation. When the channel length reaches sub-10 nm, the leak off-current appears due to the quantum tunneling effect. As the device size becomes smaller, a larger number of devices working at higher speed are integrated. Thus, larger idling energy is consumed. To overcome these problems, many emerging technologies are being explored and developed. One of the prospective technologies, called 'spintronics,' may help us to find solutions or a totally new framework of electronics.
关键词： Group-IV semiconductors,ferromagnetic semiconductors,Mn-doped,Fe-doped,electrical control of ferromagnetism,III-V semiconductors,tunneling magnetoresistance,spintronics
更新于2025-09-10 09:29:36
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Half-Metallic Ferromagnetism Character in Cr-Doped CaS Diluted Magnetic Insulator and Semiconductor: an Ab Initio Study
摘要： The overall aim of this study is to investigate theoretically the structural, electronic, and magnetic properties of calcium sulfide (CaS) doped with chromium (Cr) impurity, in order to conduct a new search dilute magnetic semiconductors (DMS) suitable for different applications in electronics and spintronics. For measuring, the physical property of this compound is implemented using the first principles approach employed in WIEN2K code. The structural characteristics are optimized using the Generalized Gradient Approximation established by Perdew-Burk-Ernzerhof (PBE-GGA). We calculate and minimize the total energy of the three ternary compounds (Ca0.75Cr0.25S, Ca0.50Cr0.50S, and Ca0.25Cr0.75S) in the paramagnetic (PM), ferromagnetic (FM), and antiferromagnetic (AFM) phase. We find all compounds stable in (FM) structure, whereas the modified Becke and Johnson local density approximation (mBJ-LDA) functional has been employed to evaluate the electronic and magnetic properties. Based on our findings, indicate that this system revealed a half-metallic ferromagnetic behavior with half-metallic gap (HM) and 100% spin-polarized at the fermi level for all chromium (Cr) concentrations. This advantageous set of properties is due to the half-metallic behavior, where the majority spin and minority spin exhibit metallic and semiconducting behaviors respectively. The chromium atom is the most important source of the total magnetic moment in these compounds (4 μβ) by comparison with magnetic moments produced by Ca and S atoms, which have minor contribution. Finally, our prediction results require an experimental confirmation in the future.
关键词： Diluted magnetic insulators (DMI),Spintronics,CaS,HM ferromagnetism,Density functional theory (DFT)
更新于2025-09-10 09:29:36
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Enhancing optical absorption in visible light of ZnO co-doped with europium and promethium by first principles study through modified Becke and Johnson potential scheme
摘要： By using first-principle calculations we studied the electronic, optical and magnetic properties of ZnO co-doped with Eu and Pm. In this calculation, we used Wien2k code based on Full potential linearized augmented plane waves (FP-LAPW) method with the modified Becke-Johnson (mBJ) approximation. This correction gives good band gap compared to experimental band gap. The introduction of Eu and Pm codoping leads to an increase in the band gap. Electrons can transit easily from the valence band to the conduction band, which results in an enhancement of visible light absorption in a wider absorption range. Absorption spectra reach a high value in visible and infrared light regions. With the significance of the obtained results, the studied compounds may potentially find spintronic and optoelectronic applications.
关键词： transmittance,Zinc Oxide,density functional theory,band gap,spintronics,Rare Earth,magnetic properties,absorption,modified Becke-Johnson,photovoltaic
更新于2025-09-10 09:29:36
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All-optical generation and ultrafast tuning of non-linear spin Hall current
摘要： Spin Hall effect, one of the cornerstones in spintronics refers to the emergence of an imbalance in the spin density transverse to a charge flow in a sample under voltage bias. This study points to a novel way for an ultrafast generation and tuning of a unidirectional nonlinear spin Hall current by means of subpicosecond laser pulses of optical vortices. When interacting with matter, the optical orbital angular momentum (OAM) carried by the vortex and quantified by its topological charge is transferred to the charge carriers. The residual spin-orbital coupling in the sample together with confinement effects allow exploiting the absorbed optical OAM for spatio-temporally controlling the spin channels. Both the non-linear spin Hall current and the dynamical spin Hall angle increase for a higher optical topological charge. The reason is the transfer of a higher amount of OAM and the enhancement of the effective spin-orbit interaction strength. No bias voltage is needed. We demonstrate that the spin Hall current can be all-optically generated in an open circuit geometry for ring-structured samples. These results follow from a full-fledged propagation of the spin-dependent quantum dynamics on a time-space grid coupled to the phononic environment. The findings point to a versatile and controllable tool for the ultrafast generation of spin accumulations with a variety of applications such as a source for ultrafast spin transfer torque and charge and spin current pulse emitter.
关键词： optical vortices,orbital angular momentum,Spin Hall effect,quantum rings,spin-orbit interaction,spintronics
更新于2025-09-10 09:29:36
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Long spin coherence length and bulk-like spin–orbit torque in ferrimagnetic multilayers
摘要： Spintronics relies on magnetization switching through current-induced spin torques. However, because spin transfer torque for ferromagnets is a surface torque, a large switching current is required for a thick, thermally stable ferromagnetic cell, and this remains a fundamental obstacle for high-density non-volatile applications with ferromagnets. Here, we report a long spin coherence length and associated bulk-like torque characteristics in an antiferromagnetically coupled ferrimagnetic multilayer. We find that a transverse spin current can pass through >10-nm-thick ferrimagnetic Co/Tb multilayers, whereas it is entirely absorbed by a 1-nm-thick ferromagnetic Co/Ni multilayer. We also find that the switching efficiency of Co/Tb multilayers partially reflects a bulk-like torque characteristic, as it increases with ferrimagnet thickness up to 8 nm and then decreases, in clear contrast to the 1/thickness dependence of ferromagnetic Co/Ni multilayers. Our results on antiferromagnetically coupled systems will invigorate research towards the development of energy-efficient spintronics.
关键词： magnetization switching,Spintronics,ferrimagnetic multilayer,spin coherence length,spin torques,bulk-like torque
更新于2025-09-10 09:29:36
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Reference Module in Materials Science and Materials Engineering || Nano-Structured Diluted Magnetic Semiconductors
摘要： Diluted magnetic semiconductors (DMS) materials have attracted much interest in recent years because of the combination of both semiconducting and magnetic properties within the same material. Among the potential applications that DMS materials can offer is spintronics which exploits both the electron charge associated with the intrinsic spin of the electron. DMS are semiconductors doped with magnetic impurities. Physical properties, like band gap energy or magnetism, are now not only a function of the particle size but also of the doping level. Therefore, ordered arrays of nanometer sized magnetic semiconductors are promising components for new devices in magneto- or spin electronics.
关键词： Diluted magnetic semiconductors,Band gap energy,Spintronics,Nanometer sized magnetic semiconductors,Magnetic impurities
更新于2025-09-09 09:28:46