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Metal halide perovskite materials (MHPs) are promising for several applications due to their exceptional properties. Understanding excitonic properties is essential for exploiting these materials. For this purpose, we focus on CsPbBr3 single crystals, which have higher crystal quality, are more stable, and have no Rashba effect at low temperatures compared to other 3D MHPs. We have estimated exciton energy positions, longitudinal-transverse splitting energy, and damping energy using low-temperature reflection spectra. Under high excitation intensity, two biexciton emissions (M-emission) and exciton–exciton scattering emission (P-emission) were observed. We assign the two M-emissions to the emission to the states of longitudinal and transverse excitons, i.e., ML and MT emissions. From the energy position of the MT emission, the biexciton binding energy has been estimated to be ∼2 meV. By analyzing P-emission obtained from the back side of the sample, we have estimated the exciton binding energy to be 17.8–23.7 meV. This estimation minimizes the influence of the wavenumber distribution in the scattering process. In addition, time-resolved transmittance measurements using pulsed white light have revealed the group velocity dispersion. Comparing experimental results with theoretical calculations using the Lorentz model clarifies that exciton dynamics in CsPbBr3 can be described with a simple Lorentz model. These insights enhance the understanding of exciton behavior and support the development of exciton-based devices using MHPs. [ABSTRACT FROM AUTHOR]

This study delves into the interplay of symmetry and structure in 2D systems to identify monolayers hosting valley physics together with the Rashba effect. Through high-throughput density functional theory calculations, 57 monolayers are identified exhibiting the Rashba effect, with the Rashba parameter α R spanning from 0 < α R < 2.0. The robustness of the Rashba parameters (α R) in these monolayers is primarily influenced by the physical parameters, highlighting the anti-crossing of Rashba-split bands and the Born effective charge (Z*). Among the 57 monolayers exhibiting the Rashba effect, the study identifies a subset of 23 monolayers presenting valley physics, demonstrating both in-plane and out-of-plane spin polarizations. The pronounced coupling of the valley and Rashba spin splitting is influenced by the in-plane and out-of-plane orbital contributions at the relevant K-points in the band spectra. In particular, the AB-type buckled structures feature these dual properties due to the presence of the broken inversion and mirror symmetries in them. Overall, the study eases the identification of monolayers with significant spin splitting and spin polarization, aiding in the design of high-performance 2D materials. [ABSTRACT FROM AUTHOR]

Investigating the interplay between charge and spin conversion in two-dimensional (2D) materials holds significant promise for futuristic electronic applications. Through density functional theory, our study delves into the charge-spin conversion and spin density dynamics in the non-magnetic SnNBr monolayer under time-reversal invariance. The breaking of out-of-plane mirror symmetry and inversion symmetry, along with the presence of spin–orbit coupling (SOC) lead to a notable momentum-dependent spin band splitting or Rashba effect induced by the inherent out-of-plane electric field. Theoretical calculations reveal not only the presence of profound Rashba spin splitting but also the coexistence of intrinsic spin Hall effects in the SnNBr monolayer. Analysis of k-resolved spin Berry curvature sheds light on the origin of the substantial intrinsic spin Hall conductivity. Furthermore, our research highlights the modulation of charge-to-spin conversion and spin density accumulation through in-plane biaxial strains. Moreover, the variation in the Rashba parameter is correlated with the changes in the built-in out-of-plane electric field and microscopic atomic orbital contributions. These findings underscore the exceptional potential of the non-centrosymmetric SnNBr monolayer for advanced spintronics, spin-orbitronics, and piezo-spintronic applications, and serve as a catalyst for further experimental investigations. [ABSTRACT FROM AUTHOR]

The Rashba spin–orbit coupling effect, primarily arising from structural-inversion asymmetry in periodic crystals, has garnered considerable attention due to its tunability and potential applications in spintronics. Its capability to manipulate electron spin without an external magnetic field opens new avenues for spintronic device design, particularly in semiconductor technology. Within this framework, 2D Rashba materials hold special interest due to their inherent characteristics, which facilitate miniaturization and engineering capabilities. In this Perspective article, we provide an overview of recent advancements in the research of 2D Rashba materials, aiming to offer a comprehensive understanding of the diverse manifestations and multifaceted implications of the Rashba effect in material science. Rather than merely presenting a list of materials, our approach involves synthesizing various viewpoints, assessing current trends, and addressing challenges within the field. Our objective is to bridge the gap between fundamental research and practical applications by correlating each material with the necessary advancements required to translate theoretical concepts into tangible technologies. Furthermore, we highlight promising avenues for future research and development, drawing from insights gleaned from the current state of the field. [ABSTRACT FROM AUTHOR]

In order to explore the interplay among heat, charge, and spin, we investigate the spin-related thermoelectricity of a hybrid double quantum dot Aharonov–Bohm interferometer with Rashba spin–orbit coupling (RSOC). Interestingly, the nonzero RSOC phase difference can induce significant spin-dependent thermoelectric transport. Not only can the strong violation of the Wiedemann-Franz law be obtained, but also a pure spin-Seebeck effect can be produced, which may serve as a pure spin-current generator. The influence of system parameters on thermoelectric coefficients (especially for spin counterparts) are analyzed in detail, and the underlying physics is further elucidated. Furthermore, the spin figure of merit can be much larger than the charge one, which, thus, provides a realistic possibility of engineering spin thermoelectric devices with high performance. These results obtained may be of interest for developing spin thermoelectric devices in the field of spin caloritronics. [ABSTRACT FROM AUTHOR]

The magnetic properties of the lattice formed by noninteracting semiconductor quantum rings in a longitudinal magnetic field are investigated. It was shown that when the value of the Rashba parameter ξ = 1.5, the magnetization varies from positive to negative with changes in the Aharonov–Bohm flux and amplitude oscillations decrease. [ABSTRACT FROM AUTHOR]

Magnetization dynamics, which determine the speed of magnetization switching and spin information propagation, play a central role in modern spintronics. Gaining its control will satisfy the different needs of various spintronic devices. In this work, we demonstrate that the surface oxidized Cu (CuOX) can be employed for the tunability of magnetization dynamics of ferromagnet/heavy metal (HM) bilayer system. The capping CuOX layer in CoFeB/W/CuOX trilayer reduces the magnetic damping value in comparison with the CoFeB/W bilayer. The magnetic damping even becomes lower than that of the CoFeB/CuOX by ∼ 16% inferring the stabilization of anti-damping phenomena. Further, the reduction in damping is accompanied by a very small reduction in the spin pumping-induced output DC voltage in the CoFeB/W/CuOX trilayer. The simultaneous observation of anti-damping and spin-to-charge current conversion could be attributed to the orbital Rashba effect observed at the HM/CuOX interface. Our experimental findings illustrate that the cost-effective CuOX can be employed as an integral part of modern spintronics devices owing to its rich underneath spin–orbital physics. [ABSTRACT FROM AUTHOR]

Electric-field modulated magnetic properties have attracted numerous research studies to elucidate the underlying physics and develop practical electronic devices. In this work, it is demonstrated that the orbital Rashba effect can be modulated by the applied electric field, which is reflected by the variation of charge-to-orbital conversion efficiency ξ under different electric fields in Py/CuOx/PMN-PT heterostructures, where ξ displays a butterfly-like behavior with the electric field, which can be attributed to the piezostrain-mediated magnetoelectric coupling, thus realizing the effective modulation of orbital torque related to the orbital Rashba effect. In addition, our first-principles calculations demonstrate that the orbital moment increases upon increasing strain, which stems from the enhanced p–d hybridization of the interfaced O and Cu atoms. Our results provide a method for modulating the orbital Rashba effect and charge-to-orbital conversion, which shows good potential for practical applications. [ABSTRACT FROM AUTHOR]

Nonreciprocal magnetotransport is one of the central topics in spintronics because of its importance for electrically probing magnetic information. Among numerous electrical probes used to read magnetic orders, unidirectional magnetoresistance (UMR), characterized by sign changes upon reversal of either current or magnetization, is currently a matter of great interest and has been identified in various spin–orbit-coupled bilayer systems composed of an (anti)ferromagnetic layer and a nonmagnetic layer with strong spin Hall effect. A recent theoretical work predicts that a spin-anomalous-Hall (SAH) UMR in those metallic conducting bilayers can originate from the spin-anomalous-Hall effect of the ferromagnetic layer and the structural inversion asymmetry. However, this type of UMR has not been reported experimentally. Here, we give the experimental evidence of spin-anomalous-Hall UMR in the light-metal/ferromagnetic-metal Cu/Co bilayers, where the emergence of net nonequilibrium spin density is attributed to the interfacial spin leakage asymmetry due to the spin memory loss effect at the Cu/Co interface and multiple spin reflections. We also show a highly tunable UMR in the Cu/Co/CuOx trilayer by varying the Cu thickness, which is due to the competition between the orbital Rashba effect in Co/CuOx and the spin-anomalous-Hall effect in Cu/Co. Our work widens the material choice for UMR device applications and provides an alternative approach to detect in-plane magnetization without an external spin polarizer. [ABSTRACT FROM AUTHOR]

Orbital currents in light metals or metal oxides without the strong spin–orbit coupling have become an important means to achieve low-power magnetization switching in spin–orbitronic devices. The orbital magnetoresistance (OMR) originated from orbital current represents a useful strategy to explore the interaction between the orbital angular momentum (OAM) and the local magnetic moment. However, systematic research works on the enhancement of OMR and the mechanism of OAM transport are seldom reported. In this study, we report a synergistically enhanced magnetoresistance effect induced by spin and orbital currents in perpendicularly magnetized Pt/Co/Cu–CuOx systems. A maximum room temperature magnetoresistance of 0.38% was observed, exceeding the spin Hall magnetoresistance (SMR) of heavy metal-based heterostructures by one order of magnitude. The enhancement of magnetoresistance is attributed to the contributions from the OMR generated by the orbital Rashba effect at the Cu/CuOx interface and SMR induced by the spin Hall effect in heavy metal Pt. These results provide a pathway to understanding of the OAM transport in magnetic multilayer films and contribute to the design and realization of energy-efficient spin–orbitronic devices. [ABSTRACT FROM AUTHOR]

The prime objective of this work is to analyze the motion of magnetic domain walls (DWs) in a thin layer of magnetostrictive material that is perfectly attached to the upper surface of a thick piezoelectric actuator. In our analysis, we consider a transversely isotropic hexagonal subclass of magnetostrictive materials that demonstrate structural inversion asymmetry. To this aim, we utilize the one-dimensional extended Landau-Lifshitz-Gilbert equations, which describe the magnetization dynamics under the influence of various factors such as magnetic fields, spin-polarized electric currents, magnetoelastic effects, magnetocrystalline anisotropy, Rashba fields, and nonlinear dry-friction dissipation. By employing the standard traveling wave ansatz, we derive an analytical expression of the most relevant dynamic features: velocity, mobility, threshold, breakdown, and propagation direction of the DWs in both steady and precessional dynamic regimes. Our analytical investigation provides insights into how effectively the considered parameters can control the DW motion. Finally, numerical illustrations of the obtained analytical results show a qualitative agreement with the recent observations. [ABSTRACT FROM AUTHOR]

The Rashba effect of polaron in RbCl triangular quantum wells under the influence of a magnetic field is theoretically studied, and the expression of the ground state energy of the polaron is obtained within the Pekar variational method. The ground state energy of the polaron splits into two branches due to the Rashba effect. This phenomenon fully demonstrates that the influence of orbit and spin interaction in different directions on the energy of the polaron is not negligible. Because the contribution of the magnetic field cyclotron resonance frequency to the Rashba spin-orbit splitting is a positive value, the energy spacing becomes larger as the magnetic field cyclotron resonance frequency increases. Due to the spin-orbit coupling interaction, the energy splits at zero field. The total energy is reduced due to the presence of phonon. Therefore, the polaron state is more stable than the bare electron state, and the polaron energy splitting is more stable. [ABSTRACT FROM AUTHOR]

The effective mass of bound polaron in an anisotropic quantum dot is calculated by using improved linear combination operator method. Under the influence of Rashba spin–orbit interaction, the effective mass of the polaron splits into two branches on the basis of zero spin. The effective mass of bound polaron is an increase function of electron–phonon coupling strength and Coulomb bound potential strength, and a decreasing function of velocity, transverse and longitudinal confinement lengths. The relations between the spin splitting effective mass and the velocity, transverse confinement length, longitudinal confinement length, electron–phonon coupling strength and Coulomb bound potential strength are also studied by us. Due to the heavy hole characteristics, the spin splitting effective mass is negative. [ABSTRACT FROM AUTHOR]

Materials with large Rashba spin splitting (RSS) and quantum spin Hall effect (QSHE) are extremely important in spintronic device applications. Based on first-principles calculations, we present H–Pb–OH, a two-dimensional (2D) hexagonal lattice material capable of achieving complete coexistence of massive RSS and QSHE. The RSS phenomenon (αR = 3.66 eV Å) in the electronic band of H–Pb–OH occurs when the system's spatial inversion symmetry is broken and there is an intrinsic electric field present. Furthermore, biaxial stress can modulate the RSS of H–Pb–OH (−8 to 8%). By examining the electronic characteristics of H–Pb–OH, we discover that there is a significant bandgap (1.12 eV) around the Fermi surface, and the system exhibits a topological invariant Z2 = 1 due to the inversion of the s-p orbitals of the Pb atoms, indicating that H–Pb–OH is a 2D topological insulator with a large topological bandgap. Our findings provide an outstanding candidate material for investigating and implementing the coexistence of RSS and QSHE. [ABSTRACT FROM AUTHOR]

The spin degree of freedom in hybrid organic–inorganic perovskites (HOIPs) has become a rapidly growing research topic in both HOIPs and spintronics fields due to its fundamental scientific significance and tight relevance with optoelectronics. The flourishing achievements of HOIP spintronics call for a timely review to summarize the key progress and guide future developments. In this review, classical spintronic phenomena based on spin‐orbit coupling (SOC) are discussed, especially Rashba splitting and related applications such as spin‐charge conversion. Owing to the unique chirality‐spin coupling, spintronics in chiral HOIPs are particularly focused on, including chirality‐induced spin selectivity (CISS). Based on the complex band structure and carrier/exciton, spin dynamics is also widely investigated and constitutes an indispensable part of HOIP spintronics. Aside from the three main threads, other spintronic phenomena such as magneto‐optical coupling and device exploration are involved as promising opportunities. Despite the continuous breakthroughs in HOIP spintronics, more efforts are required to expand material systems, explore new physics, and optimize device configurations for enhanced performance and high integration. A deep understanding of spin behaviors in HOIPs will create a new platform beyond conventional optoelectronic and photovoltaic applications. [ABSTRACT FROM AUTHOR]

While many researchers have focused on the interfacial Rashba effect, bulk Rashba materials have received considerable interest due to their potential to enhance spin–orbit torque (SOT). By utilizing GeTe as a bulk Rashba material in the role of a spin–orbit channel, GeTe/Ni81Fe19 and GeTe/Co40Fe40B20 bilayers are fabricated, and SOTs are investigated using the spin torque ferromagnetic (FM) resonance technique. In this method, damping‐like and field‐like SOTs are extracted individually, excluding thermal effects. Upon analyzing the data, a remarkable field‐like SOT efficiency of 0.40 is obtained from the GeTe/Ni81Fe19 system. This high efficiency is attributed to the enhancement of interfacial spin–orbit coupling through the bulk Rashba effect of the GeTe channel. Moreover, noticeable distinctions in SOTs are observed between the Co40Fe40B20 and Ni81Fe19 interfaces, underscoring the importance of selecting the appropriate FM layer for optimizing SOT efficiency. This study highlights the promising potential of bulk Rashba materials like GeTe in advancing SOT‐based devices. [ABSTRACT FROM AUTHOR]

We theoretically investigate the effect of Rashba spin–orbit coupling (RSO) on thermionics properties of two-dimensional semiconductor. Due to the hybridization of parabolic and linear energy dispersion, the thermal energy equipartition is modified. The thermionic emission from the lower spin branch is enhanced and that from the upper spin branch is reduced. For a double quantum well cooling structure under lower doping, the net heat transported through the structure is enhanced by RSO. The coefficient of performance (COP) is improved by about 20% in the low bias regime and around 3% in the high bias regime. Since the RSO can be further tuned by an applied field, the COP can be further optimized. [ABSTRACT FROM AUTHOR]

In the research, the effects of the Rashba spin–orbit interaction (SOI) and magnetic field have been studied on the electronic and optical properties of a Frost–Musulin (FM) quantum dot. For this goal, the Schrödinger equation has been analytically solved by the Nikiforov–Uvarov (NU) procedure, and the energy states and the wave functions have been analytically derived. Using the analytical relations for optical properties, the total refractive index change (RIC) and absorption coefficient (AC) are calculated under a magnetic field with the Rashba SOI. The findings show that both the Rashba SOI and the magnetic field have a strong effect on the energy levels, RIC, and AC. The Rashba SOI causes the energy states to split into two branches, up and down. The peak locations of the RIC and AC move to higher energies when the magnetic field and Rashba coupling are increased. [ABSTRACT FROM AUTHOR]

The order of bright and dark excitonic states in lead-halide perovskite nanocrystals is debated. It has been proposed that the Rashba effect, driven by lattice-induced symmetry breaking, causes a bright excitonic ground state. Direct measurements of excitonic spectra, however, show the signatures of a dark ground state, bringing the role of the Rashba effect into question. We use an atomistic theory to model the exciton fine structure of perovskite nanocrystals, accounting for realistic lattice distortions. We calculate optical gaps and excitonic features that compare favorably with experimental works. The exciton fine structure splittings show a nonmonotonic size dependence due to a structural transition between cubic and orthorhombic phases. Additionally, the excitonic ground state is found to be dark with spin triplet character, exhibiting a small Rashba coupling. We additionally explore the effects of nanocrystal shape on the fine structure, clarifying observations on polydisperse nanocrystals.

We study the influence of mechanical deformations on the Zeeman and Rashba effects in transition metal dichalcogenide nanotubes and their Janus variants from first principles. In particular, we perform symmetry-adapted density functional theory simulations with spin–orbit coupling to determine the variation in the electronic band structure splittings with axial and torsional deformations. We find significant effects in molybdenum and tungsten nanotubes, for which the Zeeman splitting decreases with increase in strain, going to zero for large enough tensile/shear strains, while the Rashba splitting coefficient increases linearly with shear strain, while being zero for all tensile strains, a consequence of the inversion symmetry remaining unbroken. In addition, the Zeeman splitting is relatively unaffected by nanotube diameter, whereas the Rashba coefficient decreases with increase in diameter. Overall, mechanical deformations represent a powerful tool for spintronics in nanotubes. [ABSTRACT FROM AUTHOR]

Lead halide perovskites (LHPs) containing organic parts are emerging optoelectronic materials with a wide range of applications thanks to their high optical absorption, carrier mobility, and easy preparation methods. They possess spin-dependent properties, such as strong spin–orbit coupling (SOC), and are promising for spintronics. The Rashba effect in LHPs can be manipulated by a magnetic field and a polarized light field. Considering the surfaces and interfaces of LHPs, light polarization-dependent optoelectronics of LHPs has attracted attention, especially in terms of spin-dependent photocurrents (SDPs). Currently, there are intense efforts being made in the identification and separation of SDPs and spin-to-charge interconversion in LHP. Here, we provide a comprehensive review of second-order nonlinear photocurrents in LHP in regard to spintronics. First, a detailed background on Rashba SOC and its related effects (including the inverse Rashba–Edelstein effect) is given. Subsequently, nonlinear photo-induced effects leading to SDPs are presented. Then, SDPs due to the photo-induced inverse spin Hall effect and the circular photogalvanic effect, together with photocurrent due to the photon drag effect, are compared. This is followed by the main focus of nonlinear photocurrents in LHPs containing organic parts, starting from fundamentals related to spin-dependent optoelectronics. Finally, we conclude with a brief summary and future prospects. [ABSTRACT FROM AUTHOR]

The Rashba effect appears in the semiconductors with an inversion–asymmetric structure and strong spin-orbit coupling, which splits the spin-degenerated band into two sub-bands with opposite spin states. The Rashba effect can not only be used to regulate carrier relaxations, thereby improving the performance of photoelectric devices, but also used to expand the applications of semiconductors in spintronics. In this mini-review, recent research progress on the Rashba effect of two-dimensional (2D) organic–inorganic hybrid perovskites is summarized. The origin and magnitude of Rashba spin splitting, layer-dependent Rashba band splitting of 2D perovskites, the Rashba effect in 2D perovskite quantum dots, a 2D/3D perovskite composite, and 2D-perovskites-based van der Waals heterostructures are discussed. Moreover, applications of the 2D Rashba effect in circularly polarized light detection are reviewed. Finally, future research to modulate the Rashba strength in 2D perovskites is prospected, which is conceived to promote the optoelectronic and spintronic applications of 2D perovskites. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) exhibit strong spin‐orbit coupling and structural inversion asymmetry, making them ideal for testbeds of Rashba effects and for use in spin‐related optoelectronic and spintronic applications. However, the Rashba band splitting is mainly observed in bulk MHPs so far and is rarely observed in thin films. In this study, a direct observation of Rashba band splitting in MHP thin films at room temperature is reported. By employing a silicone rubber substrate with a high thermal expansion coefficient, the out‐of‐plane tensile strain significantly reduces the activation energy of ion migration in these thin films and leads to a considerable amount of point defects. These point defects disrupt the inversion symmetry and ultimately give rise to the Rashba band splitting. These findings open up new possibilities for manipulating Rashba effects in MHP thin films through device engineering. [ABSTRACT FROM AUTHOR]

The GeTe monolayer possesses an AB binary buckled configuration, which can induce intrinsic Rashba spin splitting due to the existence of an internal electric field. However, the electronic structure obtained shows that these splittings are not present near the Fermi level, which makes it unsuitable for practical application. Based on first-principles calculations, we introduce strain engineering to manipulate the Rashba effect. Our results suggest that tensile strain can induce a remarkable Rashba spin splitting of valence band maximum (VBM). With a tensile strain of 10%, the Rashba coefficient can increase to ∼2 eVÅ, which is larger than most 2D Rashba materials. This is because the tensile strain converts the orbital component of the VBM from Te-px (Te-py) to Te-pz states. We propose a spin transistor based on the GeTe monolayer according to its Rashba effect and tunability under strain. Compared to conventional spin field-effect transistors, this transistor can achieve a shorter channel length at the nanometer level, which means that a chip can contain more transistors and integrate it into nanodevices with higher density. [ABSTRACT FROM AUTHOR]

Mechanical stacking of two dissimilar materials often has surprising consequences for heterostructure behavior. In particular, a 2D electron gas (2DEG) is formed in the heterostructure of the topological crystalline insulator Pb0.24Sn0.76Te and graphene due to contact of a polar with a nonpolar surface and the resulting changes in electronic structure needed to avoid polar catastrophe. The spintronic properties of this heterostructure with non‐local spin valve devices are studied. This study observes spin‐momentum locking at lower temperatures that transitions to regular spin channel transport only at ≈40 K. Hanle spin precession measurements show a spin relaxation time as high as 2.18 ns. Density functional theory calculations confirm that the spin‐momentum locking is due to a giant Rashba effect in the material and that the phase transition is a Lifshitz transition. The theoretically predicted Lifshitz transition is further evident in the phase transition‐like behavior in the Landé g‐factor and spin relaxation time. [ABSTRACT FROM AUTHOR]

The Dzyaloshinskii–Moriya interactions (DMIs) of Cr2O2ClI Janus monolayer are investigated using the first‐principles calculations. There are three DMI mechanisms (namely, the Half–Fert–Levy mechanism, the Fert–Levy mechanism, and the Rashba mechanism) in Cr2O2ClI Janus monolayer. The Half–Fert–Levy mechanism, by which the I atoms enhance the spin orbit coupling interaction on the type‐I Cr atoms but have no such effect on the type‐II Cr atoms, contributes to the y‐component of the DMI vector between two nearest‐neighbor Cr atoms. Originating from the strong spin orbit coupling interaction of the I atoms, the Fert–Levy mechanism results in a significant DMI vector via the Cr–I–Cr exchange path between two type‐I next‐nearest‐neighbor Cr atoms. Induced by the intrinsic electric field of the Janus structure, the Rashba mechanism results in nonzero in‐plane components of the DMI vectors. This work provides the first‐principles calculations of the DMIs of Cr2O2ClI Janus monolayer and reveals insight into the physics behind the calculated DMIs, which promote the understanding of the complicated DMIs due to multiple mechanisms in 2D magnetic Janus monolayers. [ABSTRACT FROM AUTHOR]

The strong spin–orbit coupling (SOC) in lead halide perovskites, when inversion symmetry is lifted, has provided opportunities for investigating the Rashba effect in these systems. Moreover, the strong orbital moment, which, in turn, impacts the spin-pair in singlet and triplet electronic states, plays a significant role in enhancing the optoelectronic properties in the presence of external magnetic fields in lead halide perovskites. Here, we investigate the effect of weak magnetic fields (<1 T) on the photoluminescence (PL) properties of CsPbBr 3 nanocrystals with and without Ruddlesden–Popper (RP) faults and single crystals of CH 3 NH 3 PbBr 3. Along with an enhancement in the PL intensity as a function of an external magnetic field, which is observed in both lead bromide perovskites, the PL emission red-shifts in CsPbBr 3 nanocrystals. Density-functional theory calculations of the electronic band-edge in CsPbBr 3 show almost no change in the energy gap as a function of the external magnetic field. The experimental results, thus, suggest the role of mixing of the triplet and singlet excitonic states under weak magnetic fields. This is further deduced from an enhancement in PL lifetimes as a function of the field in CsPbBr 3. In CH 3 NH 3 PbBr 3 , an increase in PL intensity is observed under weak magnetic fields; however, no changes in the peak energy or PL lifetimes are observed. The internal magnetic fields due to SOC are characterized for all three samples and found to be the highest for CsPbBr 3 nanocrystals with RP faults. [ABSTRACT FROM AUTHOR]

The present review is aimed to understand the Rashba and Dresselhaus effects from the first-principle calculations. A brief overview of first-principle density functional theory (DFT) and its global acceptance have been discussed. The discussions of the Rashba–Dresselhaus splittings, spin textures and understanding the effects from first-principle DFT calculations have been highlighted. Rashba and Dresselhaus effects have gained much attention in recent era for their highly promising applications in spintronics. In the presence of spin-orbit coupling and inherent non-centrosymmetry, while BiTeCl, TiS2Se, rhombohedral CsPbF3 and BiCoO3 compounds show large values of Rashba parameter ( α R) of ∼ 1. 9 0 , 1.10, 1.05 and 0.74 eVÅ, respectively, the single-layered semiconductor nanostructure InSb, rhombohedral BiFeO3 and Ag2BiO3 systems however depict promising values of Dresselhaus parameter ( α D) of ∼ 2. 2 0 , 0.50 and 0.15 eVÅ, respectively. The future of Rashba–Dresselhaus effects and their advancements in spintronics have also been enlightened in this paper. We believe that this study will not only help to understand the Rashba–Dresselhaus effects from first-principle calculations, but can also augment their applications in next generation spintronic devices. [ABSTRACT FROM AUTHOR]

An unexpectedly larger current-induced spin–orbit torque in oxidized Cu (CuO x )/ferromagnet (FM) than heavy-metal/FM has recently attracted intense attention in spintronic studies. Although the two mechanisms, interfacial Rashba Edelstein effect and spin-vorticity coupling, have been put forward based on the two different conductive features of CuO x , i.e. electrical insulator and gradient of electrical mobility, the detailed investigation of transport of CuO x is still lacking. Here we experimentally report the positive and negative anomalous Hall effect (AHE) in naturally oxidized normal-metal Al/Cu double films. We found that the onset temperature of AHE corresponds to magnetic transition temperature of CuO x . Furthermore, by comparing Hall resistance of the crystalline and amorphous Cu/Al double films, we identify that the positive anomalous Hall resistance attributes to magnetic moment of CuO x itself, while the negative anomalous Hall resistance can originate from the spin or orbital currents generated at the CuO x /AlO x interface interact with magnetization of CuO x and its inverse process. [ABSTRACT FROM AUTHOR]

Using Tokuda's improved linear combination operator method and variational technique, the expression of the polaron effective mass in an parabolic quantum well is derived. Due to the spin-orbit interaction, the effective mass of polaron splits into two branches. The dependence of effective mass on temperature and mean number phonons is discussed by numerical calculation. The effective mass of polaron is an increasing function of temperature and mean number phonons. The absolute value of total spin splitting effective mass increases with the increase in temperature and spin-orbit coupling parameter, and decreases with the increase in velocity. Due to the heavy hole characteristic, the spin splitting effective mass is negative. [ABSTRACT FROM AUTHOR]

This article analytically investigates the one-dimensional motion of magnetic domain walls along a thin magnetostrictive nanostrip in a trilayer stack. This study is done under the framework of the extended Landau-Lifshitz-Gilbert equation. We consider the effect of stresses generated by the piezoelectric actuator, spin-orbit interactions caused by structural inversion asymmetry (Rashba and Spin-Hall effects), and dry-friction dissipation responsible for the structural disorder in the ferromagnetic material. First, we derive an explicit analytical expression of the domain wall velocity in the steady-state regime by employing the traveling waves ansatz and realistic assumptions on the considered parameters. It is observed that the strength of magnetostriction, Rashba and Spin-Hall effects, and dry friction affect the depinning threshold and Walker-breakdown, which represent the boundaries of a steady dynamical regime. Next, we numerically illustrate the presented analytical results and find they are in qualitatively good agreement with recent observations reported in the literature. [ABSTRACT FROM AUTHOR]

Highlighted with improved long-term thermal and environmental stability, all-inorganic metal halide perovskites exhibit tunable physical properties, cost-effective synthesis, and satisfactory optoelectronic performance, attracting increasing research interest worldwide. However, a less explored feature of these materials is their strong spin–orbit coupling (SOC), which is the hidden force influencing not only band structure but also properties including magnetoresistance, spin lifetime, and singlet-triplet splitting. This review provides an overview of the fundamental aspects and the latest progress of the SOC and debate regarding Rashba effects in all-inorganic metal halide perovskites, providing critical insight into the physical phenomena and potential applications. Meanwhile, crystal structures and photophysics of all-inorganic perovskite are discussed in the context of SOC, along with the related experimental and characterization techniques. Furthermore, a recent understanding of the band topology in the all-inorganic halide perovskites is introduced to push the boundary even further for the novel applications of all-inorganic halide perovskites. Finally, an outlook is given on the potential directions of breakthroughs via leveraging the SOC in halide perovskites. [ABSTRACT FROM AUTHOR]

Graphene is a highly promising material in the field of spin electronics. Recent experiments on electron spin resonance have observed a reduction in the g-factor of graphene. In our previous paper [J. Phys. Soc. Jpn. 88, 094707 (2019)], we demonstrated that one of sources for this reduction is the diamagnetic property of graphene. However, the diamagnetic property by itself does not fully account for the magnitude of the reduction observed in the experiments. In this paper, we focus on the Rashba effect, which is caused by the work function existing near the surface of graphene. The Rashba effect tilts the spin magnetic moment to the in-plane direction of the graphene sheet, potentially reducing the g-factor. We evaluate this reduction using a simple model system incorporating the Rashba and spin Zeeman effects. We then demonstrate that the resultant g-factor is in close agreement with that observed in the prior experiments, indicating that the Rashba effect is able to account for the remaining reduction in the g-factor of graphene. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials that can achieve mutual conversion of electricity and heat has experienced remarkable growth over the past two decades. While many TE materials exhibit high levels of symmetry, characterized by pronounced band degeneracy, which contributes to their superior TE performance, there is a growing interest in materials that deviate from perfect symmetry, displaying off-centering phenomena. Such discordant structures offer intriguing properties and present unique opportunities for enhancing TE functionality. This review begins by providing an overview of key concepts and principles of thermoelectric and a list of outstanding TE materials. Subsequently, the focus shifts towards global off-centering structures and the incorporation of discordant atoms through doping strategies. The effects arising from the presence of off-centering atoms in TE materials are thoroughly explored, encompassing their impact on various aspects of electrical and thermal transport properties. Finally, this review offers a comprehensive summary of the current state of off-centering TE materials, providing valuable insights into their unique characteristics and potential for further advancements.

The quantum spin Hall state materials have recently attracted much attention owing to their potential applications in the design of spintronic devices. Based on density functional theory calculations and crystal field theory, we study electronic structures and topological properties of functionalized thallene films. Two different hydrogenation styles (Tl2H and Tl2H2) are considered, which can drastically vary the electronic and topological behaviors of the thallene. Due to the C3v symmetry of the two systems, the px and py orbitals at the Γ point have the non-Dirac band degeneracy. With spin–orbit coupling (SOC), topological nontrivial band gaps can be generated, giving rise to non-Dirac quantum spin Hall states in the two thallium hydride films. The nontrivial band gap for the monolayer Tl2H is very large (855 meV) due to the large on-site SOC of Tl px and py orbitals. The band gap in Tl2H2 is, however, small due to the band inversion between the Tl px/y and pz orbitals. It is worth noting that both the Tl2H and Tl2H2 monolayers exhibit strong Rashba spin splitting effects, especially for the monolayer Tl2H2 (αR = 2.52 eVÅ), rationalized well by the breaking of the structural inversion symmetry. The Rashba effect can be tuned sensitively by applying biaxial strain and external electric fields. Our findings provide an ideal platform for fabricating room-temperature spintronic and topological electronic devices. [ABSTRACT FROM AUTHOR]

The search for topological superconductivity (TSC) is currently an exciting pursuit, since non-trivial topological superconducting phases could host exotic Majorana modes. However, the difficulty in fabricating proximity-induced TSC heterostructures, the sensitivity to disorder and stringent topological restrictions of intrinsic TSC place serious limitations and formidable challenges on the materials and related applications. Here, we report a new type of intrinsic TSC, namely intrinsic surface topological superconductivity (IS-TSC) and demonstrate it in layered AuSn4 with Tc of 2.4 K. Different in-plane and out-of-plane upper critical fields reflect a two-dimensional (2D) character of superconductivity. The two-fold symmetric angular dependences of both magneto-transport and the zero-bias conductance peak (ZBCP) in point-contact spectroscopy (PCS) in the superconducting regime indicate an unconventional pairing symmetry of AuSn4. The superconducting gap and surface multi-bands with Rashba splitting at the Fermi level (EF), in conjunction with first-principle calculations, strongly suggest that 2D unconventional SC in AuSn4 originates from the mixture of p-wave surface and s-wave bulk contributions, which leads to a two-fold symmetric superconductivity. Our results provide an exciting paradigm to realize TSC via Rashba effect on surface superconducting bands in layered materials. The authors study the layered superconductor AuSn4 (Tc = 2.4 K) and reveal a two-fold symmetric angular dependence, consistent with unconventional pairing. They argue that the two-fold symmetry results from the Rashba-driven mixture of p-wave surface and s-wave bulk contributions. [ABSTRACT FROM AUTHOR]

Intercalation of noble metals can produce giant Rashba-type spin–orbit splittings in graphene. The spin–orbit splitting of more than 100 meV has yet to be achieved in graphene on metal or semiconductor substrates. Here, we report the p-type graphene obtained by Pt intercalation of zero-layer graphene on SiC substrate. The spin splitting of ∼200 meV was observed at a wide range of binding energies. Comparing the results of theoretical studies of different models with the experimental ones measured by spin-ARPES, XPS and STM methods, we concluded that inducing giant spin–orbit splitting requires not only a relatively close distance between graphene and Pt layer but also the presence of graphene corrugation caused by a non-flat Pt layer. This makes it possible to find a compromise between strong hybridization and increased spin–orbit interaction. In our case, the Pt submonolayer possesses nanometer-scale lateral ordering under graphene. [ABSTRACT FROM AUTHOR]

Whereas the laser is nowadays an ubiquitous technology, applications for its microwave analog, the maser, remain highly specialized, despite the excellent low-noise microwave amplification properties. The widespread application of masers is typically limited by the need of cryogenic temperatures. The recent realization of a continuous-wave room-temperature maser, using NV− centers in diamond, is a first step towards establishing the maser as a potential platform for microwave research and development, yet its design is far from optimal. Here, we design and construct an optimized setup able to characterize the operating space of a maser using NV− centers. We focus on the interplay of two key parameters for emission of microwave photons: the quality factor of the microwave resonator and the degree of spin level-inversion. We characterize the performance of the maser as a function of these two parameters, identifying the parameter space of operation and highlighting the requirements for maximal continuous microwave emission. The realization of a continuous-wave room-temperature maser reinvigorated the maser as a platform for microwave research in a broad range of applications, yet the operative conditions are still non-optimized. The authors optimize the operating space of a maser using NV- centers in terms of quality factor of the resonator and spin-level-inversion. [ABSTRACT FROM AUTHOR]

In this paper, a GaAs quantum wire is considered with a semi-parabolic lateral confinement potential in the presence of a crossed electromagnetic field with the inclusion of Rashba SOI. The effects of pressure on thermodynamic properties have been studied. To this end, first, the eigenenergies for the system have been calculated considering Rashba spin effects under electric and magnetic fields. Then a numerical analysis is done to derive the partition function and obtain the system's thermodynamic properties. The results show that at low temperatures, all four thermodynamic properties don't show much effect due to pressure. It is found that entropy increases with increasing hydrostatic pressure, whereas pressure affects mean energy and free energy in a different manner. A peak structure is observed in specific heat as a function of temperature where the peak position depends on hydrostatic pressure. [ABSTRACT FROM AUTHOR]

We report on electrical gating of superconducting bilayer NbSe2 using dual-gate field-effect transistors constructed by the van der Waals assembly of mechanically exfoliated NbSe2 and SrTiO3 thin films grown by molecular beam epitaxy. Charge carrier doping, but not a pure electric field, was found to induce changes to the superconducting resistive transition, reaching a 190 mK modulation of the critical temperature and excluding the Rashba effect. The phase space for the superconducting state beyond the Pauli limit under in-plane magnetic fields expands when the critical temperature is enhanced. Quantitative comparison with theory suggests the presence of intervalley scattering, which competes with Ising spin–orbit coupling to set the superconducting-normal phase boundary. The gating method demonstrated here may be applied to study other van der Waals layered superconductors. [ABSTRACT FROM AUTHOR]

To investigate electronic states at the interface between surfaces that exhibit unique spin-split band dispersions is an important step in the development of a new materials that can be used to spintronics device. Antimony (Sb) and bismuth (Bi) are interesting targets for studying the nature of peculiar spin properties due to spin-orbit interactions. In this study, we fabricated the Sb ultrathin films on Bi substrate. The surface structure and electronic states of Sb/Bi heterostructure was confirmed by the low-energy electron diffraction measurement and angle-resolved photoemission spectroscopy, respectively. For 2 and 3 BL Sb film on Bi substrate, we observed a "V"-shaped electronic band, which is significantly different from the electronic state of Bi thin film and freestanding Sb ultrathin film. We conclude that this band dispersion is caused by the tensile lattice strain of Sb ultrathin film and the hybridization effect of the wavefunction with the Bi substrate. [ABSTRACT FROM AUTHOR]

Spin–orbit torques (SOTs) generated by in-plane current injection in a ferromagnetic metal (FM)/heavy metal (HM) bilayer offers a new route to electrically manipulate magnetization. Here, we report on two sizable spin–orbit field contributions from the spin Hall effect and Rashba effect in NiFe/W bilayers by using the planar Hall effect. Both spin–orbit fields decrease with increasing W layer thickness. Importantly, the spin–orbit field contributing from the spin Hall effect decreases faster than the one from the Rashba effect as the thickness of W layer increases, leading to the sign change of the field-like torque at thicker W. Our results illustrate the co-contributions of the Rashba effect and the spin Hall effect to the field-like SOT in NiFe/W bilayer giving more insight into the effect of the field-like SOT in a FM/HM bilayer. [ABSTRACT FROM AUTHOR]

The van der Waals sandwich heterostructure CuInP 2 S 6 / MoSSe / CuInP 2 S 6 (CIPS/MoSSe/CIPS) has first been employed as a prototype to tune the Rashba effect. By nonvolatile controlling of the orientation of the polarization of the top ferroelectric CIPS monolayer, it is confirmed that the Rashba effect can be switched on or off at the top position of the valence band (VB) around the Γ point. More significantly, we find that the Rashba coefficient increases by almost one order of magnitude for the "on" state as compared with the freestanding MoSSe monolayer. Based on the results of first-principle calculations, it is obtained that the enhancement of the Rashba effect results from the charge transfer from the top CIPS layer to the MoSSe layer or the bottom CIPS layer, and the lifting of the d -orbit band of the light Cu atom leads to the disappearance of Rashba spin splitting at the top of the VB around the Γ point. Furthermore, the polarization orientation of the bottom CIPS layer can greatly alter the bandgap of the sandwich structure. We hope the above nonvolatile and large amplitude tuning of the Rashba effect should be useful in the design of spintronic nano-devices. [ABSTRACT FROM AUTHOR]

Lead halide perovskites (LHPs) containing organic parts are emerging optoelectronic materials with a wide range of applications thanks to their high optical absorption, carrier mobility, and easy preparation methods. They possess spin-dependent properties, such as strong spin–orbit coupling (SOC), and are promising for spintronics. The Rashba effect in LHPs can be manipulated by a magnetic field and a polarized light field. Considering the surfaces and interfaces of LHPs, light polarization-dependent optoelectronics of LHPs has attracted attention, especially in terms of spin-dependent photocurrents (SDPs). Currently, there are intense efforts being made in the identification and separation of SDPs and spin-to-charge interconversion in LHP. Here, we provide a comprehensive review of second-order nonlinear photocurrents in LHP in regard to spintronics. First, a detailed background on Rashba SOC and its related effects (including the inverse Rashba–Edelstein effect) is given. Subsequently, nonlinear photo-induced effects leading to SDPs are presented. Then, SDPs due to the photo-induced inverse spin Hall effect and the circular photogalvanic effect, together with photocurrent due to the photon drag effect, are compared. This is followed by the main focus of nonlinear photocurrents in LHPs containing organic parts, starting from fundamentals related to spin-dependent optoelectronics. Finally, we conclude with a brief summary and future prospects.

The Rashba effect appears in the semiconductors with an inversion–asymmetric structure and strong spin-orbit coupling, which splits the spin-degenerated band into two sub-bands with opposite spin states. The Rashba effect can not only be used to regulate carrier relaxations, thereby improving the performance of photoelectric devices, but also used to expand the applications of semiconductors in spintronics. In this mini-review, recent research progress on the Rashba effect of two-dimensional (2D) organic–inorganic hybrid perovskites is summarized. The origin and magnitude of Rashba spin splitting, layer-dependent Rashba band splitting of 2D perovskites, the Rashba effect in 2D perovskite quantum dots, a 2D/3D perovskite composite, and 2D-perovskites-based van der Waals heterostructures are discussed. Moreover, applications of the 2D Rashba effect in circularly polarized light detection are reviewed. Finally, future research to modulate the Rashba strength in 2D perovskites is prospected, which is conceived to promote the optoelectronic and spintronic applications of 2D perovskites.