Carrier Spin Research Articles

Spin injection from a magnetically near-compensated state in GdFeCo and inverse spin Hall effect in electron-hole compensated metal YH2.

Rare-earth-transition-metal (RE-TM) ferrimagnets are excellent materials for spin encode/decode operations via spin transport in nonmagnetic regions. This superior performance stems from two key factors. First, the antiferromagnetic coupling between RE4f and TM3d sublattices reduces both the spin-transfer-torque switching time and inter-device magnetic-coupling. Second, the RE-TM ferrimagnets function as spin injectors/ejectors, with the TM3d sublattice solely responsible for carrier spin polarization (p), similar to conventional ferromagnetic metals. We performed spin transport experiments using the sign change of p in RE-TM, which exhibits a positive value above the magnetization compensation temperature and a negative value below it. We measured temperature dependencies of the transverse resistances (RT) of electron-hole compensated metal YH2under out-of-plane spin-polarized current injection/ejection from GdFeCo (Gd:Fe:Co=25:66:9). The abrupt change in loop polarity of the out-of-plane field dependence of RT in YH2between 290 and 300 K, which aligns with the out-of-field curve of the polar Kerr rotation in GdFeCo electrodes, strongly suggests that the observed RT results from the inverse spin Hall effect (ISHE) in YH2. We analytically formulated ISHE in terms of the electron and hole spin currents injected from the spin sources, enabling regression analysis to assess the spin transport characteristics of a GdFeCo/YH2/GdFeCo magnetic double heterostructure. To explain the observed Hall voltages, enhancements in both the spin diffusion length of YH2and the spin injection efficiency are necessary.&#xD.

Kinetics of optical phonons and DP depolarization of spins in drift transport: Hot carrier spin effect in semiconductors

<p>Spin-<strong>c</strong>onserving transport of carriers is an essential requirement for the practical semiconductor-based spintronic devices. Kinetics of optical phonons and Dyakonov-Perel (DP) depolarization of spins in drift transport in semiconductor gallium arsenide (GaAs) is theoretically investigated<strong>. </strong>We consider electrons in <em>n</em>-type bulk GaAs subjected to a strong electric field, where the electron distribution is assumed to be drifted Maxwellian. The momentum drift of this distribution results in the enhanced drift velocity, and electrons with the corresponding energy emit optical hot phonons in the drifting process. The hot phonons are incorporated via the longitudinal polar optical phonon (POP) mechanism in the momentum relaxation. It is found that a finite phonon lifetime can reduce the momentum relaxation rate, which results in a delay in the runaway to higher fields, where the effect increases with the electron density. The electron spin is found to relax with the DP relaxation frequencies, and the DP spin lifetimes are found to decrease with increasing the drift field. However, a high field completely depolarizes the electron spin due to an increase of the DP spin precession frequency of the hot electrons in the POP scattering process. It is also found that the DP spin precession frequency decreases with decreasing electron temperature or increasing electron density in the moderate range. However, the findings resulting from this investigation demonstrate the hot carrier effect in the spin transport in semiconductors. The results are discussed in comparison with those obtained in earlier experimental and theoretical studies with different approaches.</p>

Room-Temperature Quantum Coherence of Reversible Photo-Generated Radical and its Film.

Electron spin qubits are becoming an important research direction in the field of quantum computing and information storage. However, the quantum decoherence has seriously hindered the development of this field. So far, few qubits exhibit long phase memory time (Tm), and even fewer qubits that can reach room temperature. Some reports show that the coherence times of radicals are generally long, so radicals may be the preferred spin carriers for qubits. Here, we demonstrate the qubit properties of a photogenerated radical (1 a) based on 2,4,6-Tri(4-pyridyl)-1,3,5-triazine (tpt, 1). More importantly, the photogenerated radical is a spin self-diluting complex, which the dilution is generally used in the investigation of qubits to reduce the interference of environment on qubits in order to overcome the decoherence of qubits. It is surprised that radical tpt has a stable Tm=1.1 μs above 20 K, even keep it to room temperature. In addition, the tpt-film prepared by the vacuum evaporation is significantly increase the T1 and Tm at low temperature.

Exchange-enhanced spin-orbit splitting and its density dependence for electrons in monolayer transition metal dichalcogenides

We show that spin-orbit splitting (SOS) in monolayers of semiconducting transition metal dichalcogenides (TMDs) is substantially enhanced by an electron-electron interaction. This effect, similar to the exchange enhancement of the electron g factor, is most pronounced for conduction band electrons (in particular, in MoS2), and it has a nonmonotonic dependence on the carrier sheet density n. That is, the SOS enhancement is peaked at the onset of filling of the higher-energy spin-split band by electrons, n*, which also separates the regimes of slow (at n<n*) and fast (for n>n*) spin and valley relaxation of charge carriers. Moreover, this density itself is determined by the enhanced SOS value, making the account of exchange renormalization important for the analysis of the spintronic performance of field-effect transistors based on two-dimensional TMDs. Published by the American Physical Society 2024

Magneto-electronic and optoelectronic attributes of half-Heusler VXPt (X = Br, Se) alloys: A first-principles study

High-spin polarized magnetic materials might be useful in spintronics applications. The spin-polarized magnetic, optical, electronic and structural attributes of half-Heusler VXPt (X = Br, Se) alloys were theoretically explored and calculated using the WIEN2k code. The ground states of the structures are optimized, and the bulk moduli and lattice constants are computed. The values obtained from the formation energies show their stability. For VBrPt, an energy gap is present in major and minority spin carriers, while for VSePt, major spin carriers exhibit an energy gap and metallic character is seen in minority spin carriers. The band structures are further illustrated deeply through the investigation of density of states. The electron density graphs depict the ionic bonding in both alloys. The magnetic moments are additionally assessed, and the recorded values support the magnetic characteristics of VBrPt and VSePt. The assessment of how the studied alloys react to light is determined by computing various parameters. The imaginary component and absorption coefficient anticipate substantial light absorption within the visible region. The calculated outcomes unveiled the potential of the examined alloys for applications in spintronics.

Examining the influence of electric field on the photoionization cross section and spin polaronic shift in a semimagnetic double quantum well

In the current research, we performed a numerical investigation of a shallow donor impurity confined in a diluted magnetic semiconductor (DMS) double quantum well (DQW) made of a Cd1−xwMnxwTe/Cd1−xbMnxbTe under the applied electric field in the z-direction. The optoelectronic properties were carried out using the effective-mass approximation and the variational method. The binding energy and photoionization cross section were examined by considering different factors such as, well width, barrier width, impurity position, and Manganese mole fraction. Additionally, the spin polaronic shift corrections to the donor binding energy, caused by the strong exchange interaction between the magnetic moment of the Mn2+ the confined carrier spin, have been examined under the aforementioned effects.

Halogenated-edge polymeric semiconductor for efficient spin transport.

Organic semiconductors (OSCs) are featured by weak spin-orbit coupling due to their light chemical element composition, which enables them to maintain spin orientation for a long spin lifetime and show significant potential in room-temperature spin transport. Carrier mobility and spin lifetime are the two main factors of the spin transport performance of OSCs, however, their ambiguous mechanisms with molecular structure make the development of spintronic materials really stagnant. Herein, the effects of halogen substitution in bay-annulated indigo-based polymers on carrier mobility and spin relaxation have been systematically investigated. The enhanced carrier mobility with an undiminished spin lifetime contributes to a 3.7-fold increase in spin diffusion length and a record-high magnetoresistance of 8.7% at room temperature. By analyzing the spin-orbit coupling and hyperfine interaction, it was found that the distance of the substitution site from the conjugated center and the nitrogen atoms in the molecules play crucial roles in spin relaxation. Based on the above results, we proposed a molecular design strategy of halogen substitution far from conjugate center to enhance spin transport efficiency, presenting a promising avenue for advancing the field of organic spintronics.

Tuning the Spin Transition and Carrier Type in Rare-Earth Cobaltates via Compositional Complexity.

There is growing interest in material candidates with properties that can be engineered beyond traditional design limits. Compositionally complex oxides (CCO), often called high entropy oxides, are excellent candidates, wherein a lattice site shares more than four cations, forming single-phase solid solutions with unique properties. However, the nature of compositional complexity in dictating properties remains unclear, with characteristics that are difficult to calculate from first principles. Here, compositional complexity is demonstrated as a tunable parameter in a spin-transition oxide semiconductor La1- x(Nd, Sm, Gd, Y)x/4CoO3, by varying the population x of rare earth cations over 0.00≤ x≤ 0.80. Across the series, increasing complexity is revealed to systematically improve crystallinity, increase the amount of electron versus hole carriers, and tune the spin transition temperature and on-off ratio. At high a population (x = 0.8), Seebeck measurements indicate a crossover from hole-majority to electron-majority conduction without the introduction of conventional electron donors, and tunable complexity is proposed as new method to dope semiconductors. First principles calculations combined with angle resolved photoemission reveal an unconventional doping mechanism of lattice distortions leading to asymmetric hole localization over electrons. Thus, tunable complexity is demonstrated as a facile knob to improve crystallinity, tune electronic transitions, and to dope semiconductors beyond traditional means.

Synthesis and EPR Studies of Zinc and Copper TPMA Metal Complexes Containing TEMPO Functionalities

A new family of stable radical‐containing polytopic ligands based on tris(2‐pyridylmethyl)amines TPMA architecture and their corresponding metal complexes have been synthesized. These molecular systems offered the possibility to investigate how various spin carriers, such as the metal ion and the organic radical, influence their EPR properties mainly through the empirical ratio of peak heights d1/d. Moreover, it has been possible to analyze how different conformations of TEMPO radical units in the molecular skeleton affect the metallic system.

Oblique spin injection to graphene via geometry controlled magnetic nanowires

We exploit the geometry of magnetic nanowires, which define 1D contacts to an encapsulated graphene channel, to introduce an out-of-plane component in the polarisation of spin carriers. By design, the magnetic nanowires traverse the angled sides of the 2D material heterostructure. Consequently, the easy axis of the nanowires is inclined, and so the local magnetisation is oblique at the injection point. As a result, when performing non-local spin valve measurements we simultaneously observe both switching and spin precession phenomena, implying the spin population possesses both in-plane and out-of-plane polarisation components. By comparing the relative magnitudes of these components, we quantify the angle of the total spin polarisation vector. The extracted angle is consistent with the angle of the nanowire at the graphene interface, evidencing that the effect is a consequence of the device geometry. This simple method of spin-based vector magnetometry provides an alternative technique to define the spin polarisation in 2D spintronic devices.

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

Transition metal (TM) ion doping in II–VI semiconductors can produce exciton magnetic polarons (EMPs) and localized EMPs containing longitudinal optical (LO) phonon coupling, which will be discussed in this paper. TM ion doping in II–VI semiconductors for a dilute magnetic semiconductor show emission via magnetic polarons (MPs) together with hot carrier effects that need to be understood via its optical properties. The high excitation power that is responsible for hot carrier effects suppresses the charge trapping effect in low exciton binding energy (8.12 meV) semiconductors, even at room temperature (RT). The large polaron radius exhibits strong interaction between the carrier and MP, resulting in anharmonicity effects, in which the side-band energy overtone to LO phonons. The photon-like polaritons exhibit polarized spin interactions with LO phonons that show strong spin–phonon polaritons at RT. The temperature-dependent photoluminescence spectra of Ni-doped ZnTe show free excitons (FX) and FXs interacting with 2LO phonon–spin interactions, corresponding to 3T1(3F) → 1T1(1G) and EMP peaks with ferromagnetically coupled Ni ions at 3T1(3F) → 1E(1G). In addition, other d–d transitions of single Ni ions (600–900 nm) appear at the low-energy side. RT energy shifts of 14–38 meV are observed due to localized states with density-of-states tails extending far into the bandgap-related spin-induced localization at the valence band. These results show spin–spin magnetic coupling and spin–phonon interactions at RT that open up a more realistic new horizon of optically controlled dilute magnetic semiconductor applications.

Ising spin-1/2 XXZ chain's quantum problems beyond the spinon paradigm.

Spin chains are correlated quantum models of great interest in quantum systems and materials exhibiting quasi-one-dimensional magnetic properties. Here, we review results on quantum problems associated with spin chains that are beyond the usual spinon paradigm. Alternatively, we use a representation valid in the thermodynamic limit, N→∞, in terms of the N spin-1/2 physical spins of the spin-1/2XXZ chain in its whole Hilbert space. It was originally introduced for the isotropic point in Carmelo et al. [Phys. Rev. B 92, 165133 (2015)], co-authored by David, and more recently extended to spin anisotropies Δ>1 in Carmelo et al. [Phys. Rev. Res. 5, 043058 (2023)] and J. M. P. Carmelo and P. D. Sacramento [Nucl. Phys. B 974, 115610 (2022); Nucl. Phys. B 997, 116385 (2023) (Corrigendum)]. The physical-spins representation accounts for the spin-1/2XXZ chain's continuous SUq(2) symmetry parameterized by q=Δ+Δ2-1∈]1,∞] and associated with q-spin Sq. Specifically, in this review we consider two quantum problems that are beyond the spinon representation: (a) Spin Bethe strings of length n that have no spinon representation, contribute to the dynamical properties of the spin-1/2XXZ chain with anisotropy Δ>1 and for n=1,2,3 were experimentally identified and realized in the zigzag materials SrCo2V2O8 and BaCo2V2O8; (b) The spin stiffness associated with ballistic spin transport at arbitrary finite temperature, which involves a huge number of energy eigenstates, many of which are generated in the thermodynamic limit from ground states by an infinite number of elementary processes. As found in Carmelo et al. [Phys. Rev. Res. 5, 043058 (2023)] and J. M. P. Carmelo and P. D. Sacramento [Nucl. Phys. B 974, 115610 (2022); Nucl. Phys. B 997, 116385 (2023) (Corrigendum)], the use of the continuous SUq(2) symmetry reveals that for anisotropy Δ>1 the Bethe strings of length n=1,2,3,… describe a number n of physical-spins Sq=0 singlet pairs that for n>1 are bound within a Sq=0 singlet configuration. Their contribution to the spin dynamical structure factor of both the spin-1/2XXZ chain in a longitudinal magnetic field and the spin chains in SrCo2V2O8 is one of the issues addressed in this paper. In addition, the SUq(2) symmetry imposes that only 2Sq out of the N physical spins are the spin carriers. We also review recent results of J. M. P. Carmelo and P. D. Sacramento ["Diffusive spin transport of the spin-1/2 XXZ chain in the Ising regime at zero magnetic field and finite temperature," (submitted) (2024)] concerning the vanishing of the contributions to finite-temperature ballistic spin transport at zero magnetic field. Within the physical-spins representation, this merely follows from the absolute value of the elementary spin currents carried by the M=2Sq spin carriers of all finite-Sq states that contribute to the spin stiffness being finite. Finally, we discuss deviations of the zigzag materials BaCo2V2O8 and SrCo2V2O8 from the one-dimensional physics described the spin-1/2XXZ chain due to selective interchain couplings.

Are Redox-Active Centers Bridged by Saturated Flexible Linkers Systematically Electrochemically Independent?

The extent to which electrophores covalently bridged by a saturated linker are electrochemically independent was investigated considering the charge/spin duality of the electron and functionality of the electrophore as a spin carrier upon reduction. By combining computational modeling with electrochemical experiments, we investigated the mechanism by which tethered electrophores react together within 4,4'-oligo[n]methylene-bipyridinium assemblies (with n=2 to 5). We show that native dicationic electrophores (redox state Z=+2) are folded prior to electron injection into the system, allowing the emergence of supra-molecular orbitals (supra-MOs) likely to support the process of the reductive σ bond formation giving cyclomers. Indeed, for Z=+2, London Dispersion (LD) forces contribute to flatten the potential energy surface such that all-trans and folded conformers are approximately isoenergetic. Then, upon one-electron injection, for radical cations (Z=+1), LD forces significantly stabilize the folded conformers, except for the ethylene derivative deprived of supra-MOs. For radical cations equipped with supra-MOs, the unpaired electron is delocalized over both heterocycles through space. Cyclomer completion (Z=0) upon the second electron transfer occurs according to the inversion of redox potentials. This mechanism explains why intramolecular reactivity is favored and why pyridinium electrophores are not independent.

Are Redox‐Active Centers Bridged by Saturated Flexible Linkers Systematically Electrochemically Independent?

AbstractThe extent to which electrophores covalently bridged by a saturated linker are electrochemically independent was investigated considering the charge/spin duality of the electron and functionality of the electrophore as a spin carrier upon reduction. By combining computational modeling with electrochemical experiments, we investigated the mechanism by which tethered electrophores react together within 4,4′‐oligo[n]methylene‐bipyridinium assemblies (with n=2 to 5). We show that native dicationic electrophores (redox state Z=+2) are folded prior to electron injection into the system, allowing the emergence of supra‐molecular orbitals (supra‐MOs) likely to support the process of the reductive σ bond formation giving cyclomers. Indeed, for Z=+2, London Dispersion (LD) forces contribute to flatten the potential energy surface such that all‐trans and folded conformers are approximately isoenergetic. Then, upon one‐electron injection, for radical cations (Z=+1), LD forces significantly stabilize the folded conformers, except for the ethylene derivative deprived of supra‐MOs. For radical cations equipped with supra‐MOs, the unpaired electron is delocalized over both heterocycles through space. Cyclomer completion (Z=0) upon the second electron transfer occurs according to the inversion of redox potentials. This mechanism explains why intramolecular reactivity is favored and why pyridinium electrophores are not independent.

Probing the metallic state, magnetic anisotropy, and large Curie temperature in CaCuFeReO[formula omitted]: Strain engineering

Rhenium-based double perovskite oxides (DPOs) are a particularly fascinating class of materials because of high carrier spin polarization, large magnetic anisotropy energy (MAE), and complex electrical behavior along with high Curie temperature (TC). Herein, we discussed the impact of biaxial ([110]) strain ranging from −5% to ＋ 5% along the ab-plane on the electronic and magnetic properties of CaCuFeReO6 (CCFRO) DPO using ab-inito calculations. The unstrained system exhibits a ferrimagnetic (FiM) spin ordering as an energetically stable magnetic ground state due to electron hopping between Fe+3/Re+5t2g and Cu+2eg orbitals along with a metallic electronic state. Moreover, [010] (b-axis) is the magnetic easy axis that produces the MAE of 5.36 meV, giving a giant MAE constant of 1.97×107 erg/cm3. The evaluated partial spin-magnetic moment on the Cu1/Cu2/Fe/Re ion is 0.14/0.44/4.04/−0.64μB, where “−” sign on the Re moment means that its spin is antiparallel to the other ions, verifying the FiM ordering in the system. Also, the eg, t2g/eg, and t2g orbital characteristics of Cu+2, Fe+3, and Re+5 ions are visible in the spin-magnetization density iso-surfaces plots, respectively. Using the classical Heisenberg model, the computed TC for the unstrained structure is 576 K, which is quite close to the experimentally reported value of 567 K. In addition, it is shown that the FiM metallic behavior in the motif is robust against biaxial ([110]) strain within the considered range. It has also been revealed that TC increased to 5.73%/3.30% for the considered range of −5% compressive/＋5% tensile strain due to improved structural distortions.

The structural, optical, electrical and radiation shielding properties of Co-doped ZnO thin films

Co:ZnO thin films are promising due to the similar ionic radii of cobalt and ZnO, and their potential for carrier spin injection, transfer, and detection. This study aims to investigate the structural, optical, electrical, and radiation shielding properties of Co-doped zinc oxide (Co:ZnO) thin films for potential applications in various fields such as semiconductors, solar cells, spintronics, and radiation shielding. The effect of commercially available Cobalt acetate tetrahydrate and Cobalt complex (Co with conjugated NN ligand) as cobalt additives on the synthesis of ZnO thin films is compared, aiming to discern their respective impacts. The dopants are incorporated in 2, 4, and 6 wt%, employing the sol-gel spin coating method.Applying cobalt complex additive as Co precursor resulted in ZnO:Co films with a superior enhancement of the electronic band gap of 2.84–3.00 eV compared to cobalt acetate precursor (2.62–2.84 eV). With the introduction of Cobalt, there is a notable change in the electrical conductivity, showcasing a decrease from 1.5x10−7 to 2.11x10−10 (S/cm). Also, radiation shielding parameters were experimentally measured in the energy range of 186.1–1764.5 keV within the scope of gamma ray spectral analysis. Exposure buildup factors (EBF) in the energy range of 15–15,000 keV were calculated up to 1–40 mean free path (mfp). Mass stopping power (MSP) and projected range values (PR) for nuclear safety applications were calculated for protons and alpha particles using the SRIM code. Thin film thicknesses were determined by using Lambert-Beer law. It was observed that the thin film thicknesses obtained from gamma spectrometry (2.090–2.628 μm) and SEM (2.157–2.725 μm) were compatible with each other.

Efficient Green Spin Light-Emitting Diodes Enabled by Ultrafast Energy- and Spin-Funneling in Chiral Perovskites.

Introducing molecular chirality into perovskite crystal structures has enabled the control of carrier spin states, giving rise to circularly polarized luminescence (CPL) in thin films and circularly polarized electroluminescence (CPEL) in LEDs. Spin-LEDs can be fabricated either through a spin-filtering layer enabled by chiral-induced spin selectivity or a chiral emissive layer. The former requires a high degree of spin polarization and a compatible spinterface for efficient spin injection, which might not be easily integrated into LEDs. Alternatively, a chiral emissive layer can also generate circularly polarized electroluminescence, but the efficiency remains low and the fundamental mechanism is elusive. In this work, we report an efficient green LED based on quasi-two-dimensional (quasi-2D) chiral perovskites as the emitting layer (EML), where CPEL is directly produced without separate carrier spin injection. The optimized chiral perovskite thin films exhibited strong CPL at 535 nm with a photoluminescence quantum yield (PLQY) of 91% and a photoluminescence dissymmetry factor (glum) of 8.6 × 10-2. Efficient green spin-LEDs were successfully demonstrated, with a large EL dissymmetry factor (gEL) of 7.8 × 10-2 and a maximum external quantum efficiency (EQE) of 13.5% at room temperature. Ultrafast transient absorption (TA) spectroscopic study shows that the CPEL is generated from a rapid energy transfer accompanied by spin transfer from 2D to 3D perovskites. Our study not only demonstrates a reliable approach to achieve high performance spin-LEDs but also reveals the fundamental mechanism of CPEL with an emissive layer of chiral perovskites.

Half Metallic Properties of the Polymorphs of Rubidium Selenide Compound

Half-metallic ferromagnets denote a specific category of compounds where one spin channel exhibits a gap at the Fermi level, contrasting with the metallic nature of the other spin channel. This distinction results in complete carrier spin polarization, reaching 100% at the Fermi level. A first-principles pseudopotential plane-wave method is utilized to examine the structural, electronic, and magnetic characteristics of RbSe across various polymorphs. Our investigation covers the RbSe compound in the CsCl (B2), NaCl (B1), ZnS (B3), NiAs (B81) and wurtzite (B4) phases. The calculations were done using the quantum ESPRESSO code within the generalized gradient approximation. The lattice parameters, bulk moduli, and their pressure derivatives agrees with prior theoretical data for cubic structures. The electronic band structures and density of states indicate the emergence of half-metallic and magnetic properties in RbSe, which stem from the existence of spin-polarized p orbitals within the Se atom. RbSe shows half-metallic behaviour in all structures studied with an integer magnetic moment of 1μB per formula unit for CsCl, NaCl, ZnS; and 2μB for NiAs and wurtzite. Results showed that most energetically stable phase of all five crystal structures studied is the CsCl-type of RbSe.

Chirality-Induced Spin Selectivity in Composite Materials: A Device Perspective.

ConspectusMagnetism is an area of immense fundamental and technological importance. At the atomic level, magnetism originates from electron "spin". The field of nanospintronics (or nanoscale spin-based electronics) aims to control spins in nanoscale systems, which has resulted in astronomical improvement in data storage and magnetic field sensing technologies over the past few decades, recognized by the 2007 Nobel Prize in Physics. Spins in nanoscale solid-state devices can also act as quantum bits or qubits for emerging quantum technologies, such as quantum computing and quantum sensing.Due to the fundamental connection between magnetism and spins, ferromagnets play a key role in many solid-state spintronic devices. This is because at the Fermi level, electron density of states is spin-polarized, which permits ferromagnets to act as electrical injectors and detectors of spins. Ferromagnets, however, have limitations in terms of low spin polarization at the Fermi level, stray magnetic fields, crosstalk, and thermal instability at the nanoscale. Therefore, new physics and new materials are needed to propel spintronic and quantum device technologies to the true atomic limit. Emerging new phenomena such as chirality induced spin selectivity or CISS, in which an intriguing correlation between carrier spin and medium chirality is observed, could therefore be instrumental in nanospintronics. This effect could allow molecular-scale, chirality controlled spin injection and detection without the need for any ferromagnet, thus opening a fundamentally new direction for device spintronics.While CISS finds a myriad of applications in diverse areas such as chiral separation, recognition, detection, and asymmetric catalysis, in this focused Account, we exclusively review spintronic device results of this effect due to its immense potential for future spintronics. The first generation of CISS-based spintronic devices have primarily used chiral bioorganic molecules; however, many practical limitations of these materials have also been identified. Therefore, our discussion revolves around the family of chiral composite materials, which may emerge as an ideal platform for CISS due to their ability to assimilate various desirable material properties on a single platform. This class of materials has been extensively studied by the organic chemistry community in the past decades, and we discuss the various chirality transfer mechanisms that have been identified, which play a central role in CISS. Next, we discuss CISS device studies performed on some of these chiral composite materials. Emphasis is given to the family of chiral organic-carbon allotrope composites, which have been extensively studied by the authors of this Account over the past several years. Interestingly, due to the presence of multiple materials, CISS signals from hybrid chiral systems sometimes differ from those observed in purely chiral systems. Given the sheer diversity of chiral composite materials, CISS device studies so far have been limited to only a few varieties, and this Account is expected to draw increased attention to the family of chiral composites and motivate further studies of their CISS applications.

An all phosphorene lattice nanometric spin valve

Phosphorene is a unique semiconducting two-dimensional platform for enabling spintronic devices integrated with phosphorene nanoelectronics. Here, we have designed an all phosphorene lattice lateral spin valve device, conceived via patterned magnetic substituted atoms of 3d-block elements at both ends of a phosphorene nanoribbon acting as ferromagnetic electrodes in the spin valve. Through First-principles based calculations, we have extensively studied the spin-dependent transport characteristics of the new spin valve structures. Systematic exploration of the magnetoresistance (MR) of the spin valve for various substitutional atoms and bias voltage resulted in a phase diagram offering a colossal MR for V and Cr-substitutional atoms. Such MR can be directly attributed to their specific electronic structure, which can be further tuned by a gate voltage, for electric field controlled spin valves. The spin-dependent transport characteristics here reveal new features such as negative conductance oscillation and switching of the sign of MR due to change in the majority spin carrier type. Our study creates possibilities for the design of nanometric spin valves, which could enable integration of memory and logic elements for all phosphorene 2D processors.