Hybrid Spin Research Articles

The electronic and optical properties of group III-V semiconductors: Arsenides and antimonides

Investigating the structural, electronic, and optical properties of zinc-blende III-V semiconductors, particularly arsenides, and antimonides, which are crucial for optoelectronic devices such as transistors, infrared detectors, and quantum technologies due to their wide range of direct bandgaps. In this work, we have employed a first-principles approach integrating G0W0 with the HSE06 hybrid functional and spin–orbit coupling (SOC) to study their fundamental properties. Traditional Density Functional Theory (DFT) methods, particularly those using Generalized Gradient Approximation (GGA) PBE functionals, tend to underestimate bandgaps, leading to discrepancies with experimental results. To address this, our study corrects the bandgap underestimation and refines the calculation of optical constants, including the dielectric function, refractive index, extinction coefficient, and absorption coefficient. Moreover, the optimized lattice constants and electronic properties derived from our computational model strongly correlate with experimental data, demonstrating the model’s reliability in predicting material properties. The findings suggest that our methods can be applied to arsenides and antimonides, offering a pathway to designing materials with optoelectronic properties involving III-V compounds and their complex heterostructures for advanced device applications.

Generation of high-order harmonics with hybrid spin and transverse orbital angular momentum from a crystalline solid

Generation of high-order harmonics with hybrid spin and transverse orbital angular momentum from a crystalline solid

Quantum analogous spin states of ultrasonic guided waves

In quantum mechanics, spin is a physical property that dominates the topological behaviors. While manifesting the spin states they reveal complex interaction of physical parameters in a topological media. The guided waves’ inherent spin states are made of real physical spin angular momentum from the superposition of elastic waves. Thus, here the elastic spin state that naturally manifests by the ultrasonic guided waves in an elastic wave guide is explained through quantum analogous perspective. Guided wave modes are the superposition of two longitudinally polarized and two transverse polarized elastic wave potentials propagating in diverging and converging pattern. Spin nature of transverse waves is well known. Spin nature of longitudinal waves is also recently being explored. However, due to the unique modal superposition of guided Rayleigh-Lamb wave modes the physical understanding of spin state is incomplete for the guided waves in a bounded media. Unlike only one hybrid spin states described in earlier works, guided waves may manifest total six with four well defined hybrid spin states explicitly derived and explained in this article. These six spin states play crucial role in the physics of spin-momentum locking of guided waves. Two spin states originated from the interaction of similar potentials and four hybris spin states originated from the interaction of potentials with different directions of wave vector and polarization vector, as emerged in guided waves. Understanding from fundamentals and exploiting the phenomena of spin-momentum locking in guided waves may have several applications in nondestructive evaluation.

Magnetically Induced Two-Phonon Blockade in a Hybrid Spin–Mechanical System

Magnetically Induced Two-Phonon Blockade in a Hybrid Spin–Mechanical System

Probing the electronic structure, optical, and transport nature of lanthanide-based ternary materials: A First-principles perspective

High thermal stability and adjustable optoelectronic properties are the unique characteristics of lanthanide-based materials. The complex interplay between unique electronic, optical, and thermoelectric characteristics of lanthanide-based ternary chalcogenides is investigated by first principles modeling. The cohesive energy values were anticipated to be −4.54 eV/atom for PrSF and −4.87 eV/atom for PrSBr suggesting PrSBr to have the greatest bonding properties and is the most stable material. The computed formation energies range from −1.3 to −3.0 (eV/f. u), demonstrating their stability. The inclusion of bromine, a more electronegative element than fluorine, produces unique hybridization patterns and spin polarization effects. Compared to PrSBr, PrSF bonding employs more effective orbital hybridization, resulting in a greater band gap. PrSF has a higher frequency dielectric constant compared to PrSBr. The absorption edges in the ε2(ω) result from optical transitions between the Pr-f, S-p, F-p, and Br-p states. As the temperature rises, the Seeback coefficients for PrSF and PrSBr decrease exponentially. The thermal conductivity spectra of PrSF and PrSBr materials exhibit a linear increase across the temperature range. As temperature rises, the concentration of carriers and mobility increases, resulting in increased electrical conductivity values.

Quantification of Hybrid Topological Spin Textures and Their Nanoscale Fluctuations in Ferrimagnets.

Noncolinear spin textures, including chiral stripes and skyrmions, have shown great potential in spintronics. Basic configurations of spin textures are either Bloch or Néel types, and the intermediate hybrid type has rarely been reported. A major challenge in identifying hybrid spin textures is to quantitatively determine the hybrid angle, especially in ferrimagnets with weak net magnetization. Here, we develop an approach to quantify magnetic parameters, including chirality, saturation magnetization, domain wall width, and hybrid angle with sub-5 nm spatial resolution, based on Lorentz four-dimensional scanning transmission electron microscopy (Lorentz 4D-STEM). We find strong nanometer-scale variations in the hybrid angle and domain wall width within structurally and chemically homogeneous FeGd ferrimagnetic films. These variations fluctuate during different magnetization circles, revealing intrinsic local magnetization inhomogeneities. Furthermore, hybrid skyrmions can also be nucleated in FeGd films. These analyses demonstrate that the Lorentz 4D-STEM is a quantitative tool for exploring complex spin textures.

Can simple 'molecular' corrections outperform projector augmented-wave density functional theory in the prediction of 35 Cl electric field gradient tensor parameters for chlorine-containing crystalline systems?

Many-body expansion (MBE) fragment approaches have been applied to accurately compute nuclear magnetic resonance (NMR) parameters in crystalline systems. Recent examples demonstrate that electric field gradient (EFG) tensor parameters can be accurately calculated for 14 N and 17 O. A key additional development is the simple molecular correction (SMC) approach, which uses two one-body fragment (i.e., isolated molecule) calculations to adjust NMR parameter values established using 'benchmark' projector augmented-wave (PAW) density functional theory (DFT) values. Here, we apply a SMC using the hybrid PBE0 exchange-correlation (XC) functional to see if this can improve the accuracy of calculated 35 Cl EFG tensor parameters. We selected eight organic and two inorganic crystal structures and considered 15 chlorine sites. We find that this SMC improves the accuracy of computed values for both the 35 Cl quadrupolar coupling constant (CQ ) and the asymmetry parameter ( ) by approximately 30% compared with benchmark PAW DFT values. We also assessed a SMC that offers local improvements not only in terms of the quality of the XC functional but simultaneously in the quality of the description of relativistic effects via the inclusion of spin-orbit effects. As the inorganic systems considered contain heavy atoms bonded to the chlorine atoms, we find further improvements in the accuracy of calculated 35 Cl EFG tensor parameters when both a hybrid functional and spin-orbit effects are included in the SMC. On the contrary, for chlorine-containing organics, the inclusion of spin-orbit relativistic effects using a SMC does not improve the accuracy of computed 35 Cl EFG tensor parameters.

Hybrid Spin and Anomalous Spin-Momentum Locking in Surface Elastic Waves.

Transverse spin of surface waves is a universal phenomenon which has recently attracted significant attention in optics and acoustics. It appears in gravity water waves, surface plasmon polaritons, surface acoustic waves, and exhibits remarkable intrinsic spin-momentum locking, which has found useful applications for efficient spin-direction couplers. Here we demonstrate, both theoretically and experimentally, that the transverse spin of surface elastic (Rayleigh) waves has an anomalous sign near the surface, opposite to that in the case of electromagnetic, sound, or water surface waves. This anomalous sign appears due to the hybrid (neither transverse nor longitudinal) nature of elastic surface waves. Furthermore, we show that this sign anomaly can be employed for the selective spin-controlled excitation of symmetric and antisymmetric Lamb modes propagating in opposite directions in an elastic plate. Our results pave the way for spin-controlled manipulation of elastic waves and can be important for a variety of areas, from phononic spin-based devices to seismic waves.

Magnetic field induced cooperativity tuning in a Fe(II)-based hybrid spin crossover network grown on 2D surfaces

Magnetic field induced cooperativity tuning in a Fe(II)-based hybrid spin crossover network grown on 2D surfaces

Hybrid spin Hall nano-oscillators based on ferromagnetic metal/ferrimagnetic insulator heterostructures

Spin-Hall nano-oscillators (SHNOs) are promising spintronic devices to realize current controlled GHz frequency signals in nanoscale devices for neuromorphic computing and creating Ising systems. However, traditional SHNOs devices based on transition metals have high auto-oscillation threshold currents as well as low quality factors and output powers. Here we demonstrate a new type of hybrid SHNO based on a permalloy (Py) ferromagnetic-metal nanowire and low-damping ferrimagnetic insulator, in the form of epitaxial lithium aluminum ferrite (LAFO) thin films. The superior characteristics of such SHNOs are associated with the excitation of larger spin-precession angles and volumes. We further find that the presence of the ferrimagnetic insulator enhances the auto-oscillation amplitude of spin-wave edge modes, consistent with our micromagnetic modeling. This hybrid SHNO expands spintronic applications, including providing new means of coupling multiple SHNOs for neuromorphic computing and advancing magnonics.

Vacuum Rabi Splitting and Kerr Effect of a Hybrid Spin–Magnon–Photon System

AbstractThe vacuum Rabi splitting and Kerr effect are investigated theoretically in a hybrid spin–magnon–photon system, where the nitrogen‐vacancy center in diamond driven by two light fields is coupled to a spherical micromagnet embedded in a superconducting coplanar waveguide resonator. The results indicate that the phenomenon of the Mollow triplet and vacuum Rabi splitting can appear by controlling the spin–magnon coupling and magnon–photon coupling. It is shown that the probe absorption spectrum can be adjusted effectively via the pump frequency detuning. Moreover, it is demonstrated that the optical Kerr effect can be tuned by changing the Rabi frequency. This work may provide a possibility for the applications in quantum information processing and quantum sensing of magnetic signal.

Observation of phononic skyrmions based on hybrid spin of elastic waves

Skyrmions with topologically stable configuration have shown a promising route toward high-density magnetic and photonic information processing due to their defect-immune and low-driven energy. Here, we experimentally report and observe the existence of phononic skyrmions as new topological structures formed by the three-dimensional hybrid spin of elastic waves. We demonstrate that the frequency-independent spin configuration leads to ultra-broadband feature of phononic skyrmions, which can be produced in any solid structure, including chip-scale ones. We further experimentally show the excellent robustness of the flexibly movable phononic skyrmion lattices against local defects of disorder, sharp corners, and even rectangular holes. Our research opens a vibrant horizon toward an unprecedented way for elastic wave manipulation and structuration by spin configuration and offers a promising lever for alternative phononic technologies, including information processing, biomedical testing, and wave engineering.

Strain effects in phosphorus bound exciton transitions in silicon

Donor spin states in silicon are a promising candidate for quantum information processing. One possible donor spin readout mechanism is the bound exciton transition that can be excited optically and creates an electrical signal when it decays. This transition has been extensively studied in bulk, but in order to scale towards localized spin readout, microfabricated structures are needed for detection. As these electrodes will inevitably cause strain in the silicon lattice, it will be crucial to understand how strain affects the exciton transitions. Here we study the phosphorous donor bound exciton transitions in silicon using hybrid electro-optical readout with microfabricated electrodes. We observe a significant zero-field splitting as well mixing of the hole states due to strain. We can model these effects assuming the known asymmetry of the hole g-factors and the Pikus-Bir Hamiltonian describing the strain. In addition, we describe the temperature, laser power and light polarization dependence of the transitions. Importantly, the hole-mixing should not prevent donor electron spin readout and using our measured parameters and numerical simulations we anticipate that hybrid spin readout in a silicon-on-insulator platform should be possible, allowing integration to silicon photonics platforms.

Balanced Light-Assisted Hybrid Spin Exchange Optical Pumping in SERF Comagnetometers

Balanced Light-Assisted Hybrid Spin Exchange Optical Pumping in SERF Comagnetometers

Tunable logic of complex variables and quantum networks on its basis

Continuous - additive-multiplicative (AM) logic is considered, in which logical operations are replaced by algebraic operations («×» and «+») or operations with vectors, and binary variables «0» and «1» are replaced by continuous scalar ones («0- 1») or complex variables. To build this logic, a continuous analogue of the canonical form of Boolean logic is used in the form of a perfect disjunctive or conjunctive normal form (KAM logic). A feature of KAM logic is a continuous dependence on input variables and a potential variety of continuous logic functions. Based on the previously proposed «fuzzy» (distributed) continuous function, in the form of a superposition of «clear» functions, and the tunable QAM element circuit that implements it, this element is generalized to a network QAM element with several tunable outputs. The multiplication functions in this QAM element can be performed using a known memristor, which can be replaced by a memtransistor based on a field effect transistor. In quantum QAM networks, these elements are, respectively: «k-memristor» and «k-memtransistor». One of the options for a k-memtransistor is a composite hybrid spin-field-effect transistor based on a planar spin valve with magnetic memory and a field-effect transistor with a ferroelectric memory. It is noted that the main technological problem of quantum QAM networks based on such a hybrid spin transistor is the creation of planar conducting and ferromagnetic elements based on ultrathin metallic and ferromagnetic films on silicon.

A New Symbolic Time Series Analysis Method Based on Time-to-Space Mapping, through a Symmetric Magnetic Field, Quantized by Prime Numbers

This work presents a new analysis method for two-symbol symbolic time series based on the time-to-space mapping achieved through a device of current carrying circular rings. An algorithm based on the theory of prime numbers is proposed for the approximate estimation of the stratified magnetic field produced by the aforementioned device. The main property of the specific algorithm is that it quantizes the stratified magnetic field. If a two-symbol symbolic time series is used to determine the flow directions of the rings’ currents, a time-to-space mapping of the dynamics of the system producing the time series is observed. A unique “fingerprint” of the symbolic dynamics is shaped by the spatial allocation of the values of the six-valued symmetric quantized magnetic field produced by the device. This allows for the quantitative evaluation of the original system’s dynamics by analyzing the resultant quantized magnetic field values space allocation, in a spectrum ranging from the lack of dynamics (randomness) to the presence of dynamics at all scales (criticality). Two examples of application–corresponding to the extremes of the dynamics spectrum, specifically, for symbolic time series resulting from (a) a random numbers generator and (b) the spin alternation of 2D-Ising in its critical state, verify the reliable time-to-space mapping of the involved symbolic dynamics. Moreover, an application to the symbolic sequence produced by the DNA of the GAPDH (Glyceraldehyde-3-Phosphate Dehydrogenase) human gene is presented as a real-world, intermediate dynamics case. The proposed symbolic time series analysis method presents the advantage that can take into account information related to both symbols, which is particularly useful in analyzing two-symbol time series of relatively short length where the probabilities of occurrence of the two symbols are not equal. By inferring the universality class of an artificial-neural-network-based hybrid spin model through the value of the critical exponent δ, it is shown that for such time series, the proposed method provides a unique way to expose the real dynamics of the underlying complex system, in contrast to the analysis of waiting times in the time domain that leads to an ambiguous quantitative result.

Geometric Landau-Zener-Stückelberg-Majorana interferometry for hybrid spin registers

Hybrid systems of electron and nuclear spins are a fundamental building block for scalable quantum information processing. Here we propose a fast and high-fidelity control scheme based on geometric Landau-Zener-St\"uckelberg-Majorana interferometry, using a nitrogen-vacancy center in diamond as an example. When this hybrid spin multilevel system is driven through avoided crossings, geometric phases accumulate in each spin subspace and manifest as interference patterns in the dynamics of the whole system. We systematically study the effects of various decoherence mechanisms and fluctuations of control parameters on this geometric phase process. We also consider the application of quantum memory, where electron spins are used as a processing qubit and nuclear spins are used as a storage qubit. This scheme can achieve a transfer fidelity of 0.985 and a total storage fidelity of 0.96. These results pave the way for geometric coherent manipulations on a variety of hybrid quantum platforms.

Insights and Implications of Intricate Surface Charge Transfer and sp3-Defects in Graphene/Metal Oxide Interfaces.

Adherence of metal oxides to graphene is of fundamental significance to graphene nanoelectronic and spintronic interfaces. Titanium oxide and aluminum oxide are two widely used tunnel barriers in such devices, which offer optimum interface resistance and distinct interface conditions that govern transport parameters and device performance. Here, we reveal a fundamental difference in how these metal oxides interface with graphene through electrical transport measurements and Raman and photoelectron spectroscopies, combined with ab initio electronic structure calculations of such interfaces. While both oxide layers cause surface charge transfer induced p-type doping in graphene, in sharp contrast to TiOx, the AlOx/graphene interface shows the presence of appreciable sp3 defects. Electronic structure calculations disclose that significant p-type doping occurs due to a combination of sp3 bonds formed between C and O atoms at the interface and possible slightly off-stoichiometric defects of the aluminum oxide layer. Furthermore, the sp3 hybridization at the AlOx/graphene interface leads to distinct magnetic moments of unsaturated bonds, which not only explicates the widely observed low spin-lifetimes in AlOx barrier graphene spintronic devices but also suggests possibilities for new hybrid resistive switching and spin valves.

Spin polarization characteristics of hybrid optically pumped comagnetometers with different density ratios.

We investigate the effects of the density ratio of K-Rb hybrid cells on the alkali metal-noble gas comagnetometers. Bloch equations simplified with the density ratio and average-pumping-rate model are presented for numerical simulation, which simplifies equations of complete hybrid spin ensemble and problem of polarization gradient. The spin polarizations of electron and nucleon, total electronic relaxation rates, and the spin-exchange efficiencies are measured with cells of different density ratios. The results are in good agreement with our equivalent model. Based on our theoretical analysis, the K-Rb-21Ne comagnetometer achieves maximum output signal by optimizing the combination of density ratio and optical power density. The density ratio is critical to the homogeneity of spin polarization and efficiency of hyperpolarization. The method in this work finds a way to optimize the sensitivity of comagnetometers, which is significant for angular-rotation sensors and new physics research.

Optimization of a quantum control sequence for initializing a nitrogen-vacancy spin register

Implementation of many quantum information protocols requires an efficient initialization of the quantum register. In the present paper, we optimize a population trapping protocol for initializing a hybrid spin register associated with a single nitrogen-vacancy (NV) center in diamond. We initialize the quantum register by polarizing the electronic and nuclear spins of the NV with a sequence of microwave, radio-frequency, and optical pulses. We use a rate equation model to explain the distribution of population under the effect of the optical pulses. The model is compared to the experimental data obtained by performing partial quantum state tomography. To further increase the spin polarization, we propose a recursive protocol with optimized optical pulses. We also discuss the role of the relative values of the nuclear- and electronic-spin pumping rate in achieving the maximum degree of spin polarization.