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We have observed a transition from single to double hysteresis of nuclear spin polarization (NSP) with increasing magnetic field in a single InAlAs self-assembled quantum dot, which means the birth of a third stable branch that depends on the field strength. This NSP transition behavior could not be reproduced by standard model calculations using a fixed electron–nuclear spin correlation time τ c under different external field conditions. By introducing the field dependence of τ c , we were able to successfully reproduce the observed NSP transition. This finding on the phenomenological description of the magnetic field dependence will be a future highlight of τ c . [ABSTRACT FROM AUTHOR]

High-performance and stable spintronic devices have garnered considerable attention in recent years. Based on first-principle and Monte Carlo calculations, we demonstrate that under reasonable carrier doping, H-VSe2 exhibits 100% spin polarization, a magnetic anisotropy energy of 581 μeV, a tunable easy-axis, and a Curie temperature of 330 K. Moreover, Dzyaloshinskii–Moriya interactions in H-VSe2 and magnetic hysteresis loops are determined theoretically for the first time, which provides more precise and comprehensive descriptions of its magnetic properties under finite temperatures and external magnetic field. This work suggests that H-VSe2 is a powerful candidate for spintronic devices, and it provides solid theoretical support for future experiments. [ABSTRACT FROM AUTHOR]

Understanding the electronic transport properties of low-dimensional devices has increased dramatically in recent decades, especially for those with a promising future for application in nanotechnology. Among these nanoscopic systems are molecular systems, particularly organic molecules such as catechol, representing the small piece of a potential conductor assembled through larger biomolecules and inserted between two or more metal contacts. In this work, we present a theoretical description of the electronic transport of catechol, based on its π -conjugated aromatic system, under an external magnetic field stimulus, which is transverse to the alignment of the molecule. Thus, we analyze catechol's spintronic properties through the magnetoresistance generated by this field. We model the molecule using a tight-binding Hamiltonian and Green's functions; the transmission probability is calculated by means of the Fisher-Lee relation, and the characteristic current–voltage, spin polarization, and magnetoresistance curves based on Landauer's approach for two linking models of catechol to the metallic contacts. The results suggest a strong dependence on the spin direction of the charge carriers and the Zeeman energy (E z) on the Fermi level, generating a switch-like mechanism going from conducting to semiconducting material. This behavior opens a potential application of these catechol-based systems in future spintronic devices. [ABSTRACT FROM AUTHOR]

We theoretically study the magnetic phase transition of condensed exciton-polariton microcavities in an applied magnetic field. When the magnetic field is strong, all polariton spins are polarized parallel to the magnetic field as usual. On the contrary, in the weak magnetic-field region, the polariton polarization degree is negative, namely, anti-parallel to the magnetic field. For a strong magnetic field, the magnetic phase of the polaritons arises and leads to a paramagnetic, while around a weak magnetic field, with zero exciton–photon detunings, and weak Rabi splitting the spin polarization of the polaritons leads to a diamagnetic. Thus, magneto-polariton phase transition polarization originates from the competition between the polariton Zeeman effect and polariton–polariton interactions. Moreover, the polariton polarization strongly depends on the exciton–photon detuning and Rabi splitting and has a large negative value as they are both small. At last, we compare our theoretical results with the experiments and find they match each other very well. [ABSTRACT FROM AUTHOR]

Electron transport through a variety of helical structures has been shown to exhibit high-efficiency spin filtering, which is called chirality-induced spin selectivity (CISS). In this paper, we consider a helical chain of atomic p orbitals, which has been employed as a model in exploring the mechanism of CISS in previous theories, and show that the interatomic hopping along the helical chain induces an effective magnetic field (EMF) acting on the atomic orbital angular momentum (OAM). In chains where the curvature and torsion of the helix are small, we find that the EMF on the binormal component of the atomic OAM is created by the curvature, while that on the tangential component is produced by the torsion. We show that such coupling of the atomic OAM and the interatomic hopping leads to current-induced orbital and spin polarizations. We expect that the present coupling, which is expressed locally, can be used to estimate orbital and spin polarizations locally induced in molecules and solids. [ABSTRACT FROM AUTHOR]

Magnetic field effects have received widespread attention due to their ability to enhance the process of water splitting at multiple scales. However, a systematic and comprehensive understanding of the source of the magnetic effect and the magnetic modulation of magnetic catalysts is lacking. This perspective focuses on recent advancements in harnessing external magnetic field to improve electrocatalytic water splitting and suggests future directions. First, the mechanism of several magnetic effects and their effects on water splitting are elaborated in detail, including the magnetohydrodynamic effect, magnetothermal effect, spin polarization effect, and magnetoresistance effect. Then, the classification and construction strategies of magnetic effect catalysts are summarized, primarily divided into single metal/alloy catalysts, metal oxide-based catalysts, and other magnetic catalysts. Finally, the challenges and potential perspective of magnetic field-enhanced water splitting are discussed, including mechanism study, in situ characterization, and multi-field synergy effects. [ABSTRACT FROM AUTHOR]

An experimental and computational optical pump-probe model is constructed, which utilizes two ultrafast pump pulses within the repetition period of a mode-locked laser to generate electron spin polarization. This report focuses on the effects of resonant spin amplification induced by an infinite train of the two-pump pulses. The first pump pulse is used to generate ordinary resonant spin amplification spectra, while the second pump pulse is used to manipulate the generated spectra. This model gives control of the accumulation of spin polarized electrons along a magnetic field by selecting the temporal separation of the two-pump pulses. The computational model accurately predicts and agrees with the experimental results, which shows manipulation of resonant spin peaks that are no longer entirely dependent on the external magnetic field. This two-pump model and the associated manipulations of resonant spin peaks can be used as a platform to construct and conceptualize resonant spin amplification-based optospintronic devices and applications. [ABSTRACT FROM AUTHOR]

Molecular spin systems based on photoexcited triplet pairs formed via singlet fission (SF) are attractive as carriers of quantum information because of their potentially pure and controllable spin polarization, but developing systems that offer optical routes to readout as well as initialization is challenging. Herein, we characterize the electron spin magnetic resonance change in the photoluminescence intensity for a tailored organic molecular crystal while sweeping a microwave drive up to 10 GHz in a broadband loop structure. We observe resonant transitions for both triplet and quintet spin sublevel populations showing their optical sensitivity and revealing the zero-field parameters for each. We map the evolution of these spectra in both microwave frequency and magnetic field, producing a pattern of optically detected magnetic resonance (ODMR) peaks. Fits to these data using a suitable model suggest significant spin polarization in this system with orientation selectivity. Unusual excitation intensity dependence is also observed, which inverts the sign of the ODMR signal for the triplet features, but not for the quintet. These observations demonstrate optical detection of the spin sublevel population dictated by SF and intermolecular geometry, and highlight anisotropic and multi-scale dynamics of triplet pairs. [ABSTRACT FROM AUTHOR]

We investigate the magnetic properties of La2/3Sr1/3MnO3 (LSMO) membranes released from an SrTiO3 (STO) substrate by selectively etching an Sr4Al2O7 sacrificial buffer layer. The magnetic moment and Curie temperatures (TC) of the released LSMO membranes improve significantly over their substrate-bound counterparts. We attribute these enhancements to suppressing strain and oxygen octahedral rotations that are present in substrate-bound films. Moreover, comparing the magnetic hysteresis loops obtained with magnetic fields applied along several crystallographic orientations demonstrates enhanced (weakened) perpendicular (in-plane) magnetic anisotropy in the released LSMO membranes. Our results contribute to potential applications of released LSMO membranes toward flexible spintronics devices, where high spin polarization and TC are desired. [ABSTRACT FROM AUTHOR]

The magnetic field is one of the widely used external stimuli to manipulate magnetic skyrmions. On the other hand, the skyrmion Hall effect can force the skyrmion to move perpendicular to the driving direction, which may lead to the annihilation of the skyrmion at the sample edge. Here, we study a skyrmion guide based on a nanotrack, where the skyrmion is controlled by the spin-transfer torque or spin–orbit torque in the presence of an in-plane field. The effects of spin-torque parameters, spin polarization directions, and magnetic field with an appropriate magnitude on the skyrmion motion are explored. Both static and dynamic properties of the skyrmion are demonstrated through micromagnetic simulations. Our results can be useful for the development of topological transport channels for spintronic devices. [ABSTRACT FROM AUTHOR]

Coupled pairs of nuclear spin-1/2 support one singlet state and three triplet states. Transitions between the singlet state and one of the triplet states may be driven by an oscillating low-frequency magnetic field, in the presence of couplings to a third nuclear spin, and a weak bias magnetic field. The oscillating field is in the same direction as the bias field and is called a WOLF (Weak Oscillating Low Field) pulse. Application of a WOLF pulse allows for the generation of strong nuclear hyperpolarization of 13C nuclei, starting from the nuclear singlet polarization of a 1H spin pair, associated with the enriched para-spin isomer of hydrogen gas. Hyperpolarization is demonstrated for two molecular systems. [ABSTRACT FROM AUTHOR]

Recently, experimental 2D magnetic CrSe2 and CrTe2 inspired the study on their Janus CrSeTe, which breaks the mirror symmetry of Cr–Se(Te)–Cr. However, the CrSeTe monolayer possesses a lower Curie temperature and the in-plane magnetic anisotropy, and few works concerned both its zigzag- and stripy-antiferromagnetic states, which are crucial to determine the magnetic ground state and magnetic transition temperature. In this Letter, using first-principles calculations and Monte Carlo simulations, we systematically explore the strain, carrier-doping, and electric field effects on magnetic and electronic properties of monolayer CrSeTe. We demonstrate that monolayer CrSeTe preserves ferromagnetism in a large range of whether strain or doping. The estimated Curie temperature can be increased from 167 K to the room-temperature by the combination of 4% tensile strain and 0.1 e doping due to the enhanced ferromagnetic Cr–Se(Te)–Cr super-exchange interaction. Interestingly, either a small tensile strain (1%) or a low hole doping (0.025 h) can induce the transition of the easy axis from in-plane to out-of-plane due to the increased out-of-plane magnetic anisotropy from hybridized pz and py orbitals of Te atoms. In addition, the spin polarization is improved by over 60% by the tensile strain. Our results suggest that small strain and low carrier-doping induced room-temperature ferromagnetism, large out-of-plane magnetic anisotropy, and high spin polarization make CrSeTe useful in 2D spintronic applications and will stimulate broad studies on the regulation of magnetic and electronic properties of this class of magnetic Janus monolayers. [ABSTRACT FROM AUTHOR]

We present the observation of field-free spin-orbit-torque (SOT) switching of magnetization in a ferromagnetic semiconductor (Ga,Mn)As film with four-fold in-plane magnetic anisotropy. Magnetization switching is demonstrated between two orthogonal in-plane easy axes through planar Hall resistance measurements as a current is scanned in the absence of a magnetic field. The chirality of the switching of the current hysteresis loop is consistent with SOT arising from spin polarization caused by Dresselhaus- and Rashba-type spin-orbit-induced effective magnetic fields in the (Ga,Mn)As film. The chirality of magnetization switching can be reversed either by changing the direction of the initial magnetization or by applying a constant external magnetic field bias. The SOT magnetization switching between two states was consistently repeated by applying sequential current pluses with alternating polarities, indicating the potential for developing a field-free SOT device. [ABSTRACT FROM AUTHOR]

The generation of perpendicular effective magnetic field or perpendicular spins (σz) is central for the development of energy-efficient, scalable, and external-magnetic-field-free spintronic memory and computing technologies. Here, we report the first identification and the profound impacts of a significant effective perpendicular magnetic field that can arise from asymmetric current spreading within magnetic microstrips and Hall bars. This effective perpendicular magnetic field can exhibit all the three characteristics that have been widely assumed in the literature to "signify" the presence of a flow of σz, i.e., external-magnetic-field-free current switching of uniform perpendicular magnetization, a sin 2φ-dependent contribution in spin-torque ferromagnetic resonance signal of in-plane magnetization (φ is the angle of the external magnetic field with respect to the current), and a φ-independent but field-dependent contribution in the second harmonic Hall voltage of in-plane magnetization. This finding suggests that it is critical to include current spreading effects in the analyses of various spin polarizations and spin–orbit torques in the magnetic heterostructure. Technologically, our results provide a perpendicular effective magnetic field induced by asymmetric current spreading as a novel, universally accessible mechanism for efficient, scalable, and external-magnetic-field-free magnetization switching in memory and computing technologies. [ABSTRACT FROM AUTHOR]

We address the temperature influence on the precessional motion of electron spins under a transverse magnetic field, studied in GaAs/AlGaAs triple quantum wells, using pump-probe Kerr rotation. In the presence of an applied in-plane magnetic field, the TRKR measurements show the robustness of carrier's spin polarization against temperature, which can be easily traced in an extended range up to 250 K. By tuning the pump-probe wavelength to the exciton bound to a neutral donor transition, we observed a remarkably long-lasting spin coherence (with dephasing time T 2 * > 14 ns) limited by the spin hopping process and exchange interaction between the donor sites, as well as the ensemble spread of the g-factor. The temperature dependent spin dephasing time revealed a double linear dependence due to the different relaxation mechanisms active in respective temperature ranges. We observed that the increase in sample temperature from 5 K to 250 K leads to a strong T 2 * reduction by almost 98%/97% for the excitation wavelengths of 823/821 nm. Furthermore, we noticed that the temperature increase not only causes the reduction of spin lifetime, but can also lead to the variation of the electron g-factor. Additionally, the spin dynamics were studied through the dependencies on the applied magnetic field and optical pump power. [ABSTRACT FROM AUTHOR]

We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets. [ABSTRACT FROM AUTHOR]

We show a topological spin texture called "bimeronium" in magnets with in-plane magnetization. It is a topological counterpart of skyrmionium in perpendicularly magnetized magnets and can be seen as a combination of two bimerons with opposite topological charges. We report the static structure and spin-orbit-torque-induced dynamics of an isolated bimeronium in a magnetic monolayer with frustrated exchange interactions. We study the anisotropy and magnetic field dependences of a static bimeronium. We also explore the bimeronium dynamics driven by the damping-like spin-orbit torque. We find that the bimeronium shows steady rotation when the spin polarization direction is parallel to the easy axis. Moreover, we demonstrate the annihilation of the bimeronium when the spin polarization direction is perpendicular to the easy axis. Our results are useful for understanding the fundamental properties of bimeronium structures and may offer an approach to build bimeronium-based spintronic devices. [ABSTRACT FROM AUTHOR]

We perform a numerical study on the spin-resolved transport in a quantum wire (QW) under the modulation of both Rashba spin-orbit coupling (SOC) and a perpendicular magnetic field by using the developed Usuki transfer-matrix method in combination with the Landauer-Büttiker formalism. Wide spin filtering energy windows can be achieved in this system for unpolarized spin injection. In addition, both the width of energy window and the magnitude of spin conductance within these energy windows can be tuned by varying Rashba SOC strength, which can be apprehended by analyzing the energy dispersions and spin-polarized density distributions inside the QW, respectively. Further study also demonstrates that these Rashba-SOC-controlled spin filtering energy windows show a strong robustness against disorders. These findings may not only benefit to further understand the spin-dependent transport properties of a QW in the presence of external fields but also provide a theoretical instruction to design a spin filter device. [ABSTRACT FROM AUTHOR]

The magnetization reversal in several nanoscopic systems is driven by the nucleation and propagation of a vortex structure that is very sensitive to the application of a magnetic field or a spin polarized current. In particular in a dot, the vortex profile is strongly affected by anisotropy, however, its role on the core behavior has not been clarified. In the present work, we investigate the influence of a perpendicular anisotropy on the annihilation and shape of magnetic vortex cores in permalloy disks. We used both micromagnetic simulations with the OOMMF code, and the analytical rigid core model that assumes that the shape of the core does not change during the hysteresis cycle. Under both approaches, the annihilation field decreases with increasing perpendicular anisotropy for almost all the structures investigated. Also a deformation of the vortex core profile is evidenced from the micromagnetic simulations, for larger anisotropy and/or dot thickness. For every dot thickness, this change does not depend on the dot radius, but on the relative distance of the core from the center of the dot. [ABSTRACT FROM AUTHOR]

In an easy-plane antiferromagnet with the Dzyaloshinskii–Moriya interaction (DMI), magnons are subject to an effective spin-momentum locking. An in-plane temperature gradient can generate interfacial accumulation of magnons with a specified polarization, realizing the magnon thermal Edelstein effect. We theoretically investigate the injection and detection of this thermally driven spin polarization in an adjacent heavy metal with a strong spin Hall effect. We find that the inverse spin Hall voltage depends monotonically on both temperature and the DMI but non-monotonically on the hard-axis anisotropy. Counterintuitively, the magnon thermal Edelstein effect is an even function of a magnetic field applied along the Néel vector. [ABSTRACT FROM AUTHOR]

Antiferromagnetic materials are expected to trigger the revolution of spintronic applications because they are robust against the perturbation of magnetic fields, produce no stray fields, and display ultrafast dynamics. To design antiferromagnetic devices, the generation and manipulation of spin-polarized current in antiferromagnetic materials are vital. Unfortunately, it has long been believed that spin-polarized current could not be achieved in collinear antiferromagnetic materials because of the symmetry of spin sublattices. Inspired by the possibility of breaking the symmetry using a bias voltage, a special Au/NiO/Au junction is proposed and constructed along the [111] direction of NiO using the collinear NiO antiferromagnetic insulator as a prototype. It was found that the symmetry of spin sublattices was broken by an external bias, which induces a nonequivalent transport for spin-up and spin-down currents, that is, the appearance of spin-polarized current. Unexpectedly, this study found that the magnitude and sign of spin polarization could be adjusted by varying the bias. A positive spin polarization up to 80% was obtained at ∼ 0.9 V, and the spin polarization turned negative when the bias voltage was beyond 1.6 V. The related physical mechanisms were explored and clarified by analyzing spin-resolved transmission, kǁ-resolved density of states, and layer-resolved local density of states of Au/NiO/Au, etc. The effects of NiO layer thicknesses, different electrodes, and interfacial disorders on the spin polarization were also analyzed and found to offer promising applications. This study provides new physical insight into spin-polarized current transport in collinear antiferromagnetic materials and greatly contributes to the development of novel antiferromagnetic spintronic devices. [ABSTRACT FROM AUTHOR]

In this paper, we experimentally study the saturation effect of rubidium atomic magnetic resonance. A pump beam is applied to create atomic spin polarization, a radio frequency (RF) magnetic field is used to drive the spin precession about a static magnetic field, and an off-resonant linearly polarized probe beam is applied to detect the spin dynamics based on the Faraday-rotation effect. When the RF magnetic field intensity becomes strong, a saturation effect is observed. We measure the resonant peak under strong RF magnetic field driving and obtain a saturation dip as an indication of the saturation effect. Furthermore, we show that the line-width of the saturation dip is much smaller than that of magnetic resonance. Accordingly, the sensitivity of the precision measurement based on the saturation dip can be significantly improved. The relations between the saturation dip in the resonant peak and the driving RF magnetic field intensity, as well as pumping intensity, are also studied in our experiment. [ABSTRACT FROM AUTHOR]

Herein, we report a Na deficient single phase sodium bismuth titanate perovskite exhibiting ferromagnetism with reduced leakage conductivity and a self-biased high magnetoelectric (ME) coupling coefficient at room temperature (27 °C). Observed ferromagnetism is induced by sodium cation vacancy dominated by spin polarization of holes in the valence band. An unexpected high ME coupling coefficient of about 4.18 mV/cm Oe, observed at zero DC magnetic bias field, is relatively large and juxtapose to other single phase multiferroics including BiFeO3. This study opens up an altered strategy in designing multiferroic materials with reinforced ME coupling at room temperature. [ABSTRACT FROM AUTHOR]

Relationship between FeCo crystalline orientation and magnetic properties of TbFeCo/FeCo/Ta trilayer films was investigated. FeCo crystalline orientation could be controlled by changing FeCo deposition rate. Ferromagnetic Hall effect observation clarified that perpendicular component of magnetization in FeCo layer of TbFeCo/FeCo(001)/Ta were better than that of TbFeCo/FeCo(110)/ Ta. Lattice spacing of both FeCo(001) films and FeCo(110) ones in the TbFeCo(50 nm)/FeCo (X nm) was also observed. Expansion ratios of FeCo(001) toward film normal direction were higher than that of FeCo(110) as increasing FeCo film thickness, and this indicated that FeCo(001) films were more favorable for magnetic coupling with rare-earth transition metal (RE-TM) alloy films than FeCo(110) ones when FeCo films become thick. However investigation of relationship between FeCo expansion ratios and magnetic properties of TbFeCo/FeCo(001) or (110) (X nm)/Ta trilayer films showed that squareness ratios of specimens with FeCo(001) were worse than that with FeCo(110). [ABSTRACT FROM AUTHOR]

Theoretical studies of spin dependent transport in Fe/Cr/MgO/Fe tunnel junctions with noncollinear alignment of magnetizations of metallic layers comprising these magnetic tunnel junctions are presented. Calculations are performed with use of nonequilibrium Green function technique in the framework of the Keldysh formalism. Electronic band structure of ferromagnetic electrodes is modeled within a two-band model with majority and minority states being s-like and d-like electrons, respectively. Furthermore, interfacial s-d hybridization is taken into account and calculated using perturbation corrections for the wave and Green functions. It is shown that in the presence of Cr layer at the Fe/MgO interface, the contribution from s-d hybridization to the total current is much stronger in the antiparallel magnetizations configuration compared to the parallel one leading to decrease in tunnel magnetoresistance values in agreement with earlier reports. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenide monolayers are highly interesting for potential valleytronic applications due to the coupling of spin and valley degrees of freedom and valley-selective excitonic transitions. However, ultrafast recombination of excitons in these materials poses a natural limit for applications so that a transfer of polarization to resident carriers is highly advantageous. Here, we study the low-temperature spin-valley dynamics in nominally undoped and n-doped MoSe2 monolayers using time-resolved Kerr rotation. In the n-doped MoSe2, we find a long-lived component of the Kerr signal which we attribute to the spin polarization of resident carriers. This component is absent in the nominally undoped MoSe2. The long-lived spin polarization is stable under applied in-plane magnetic fields. Spatially resolved measurements allow us to determine an upper boundary for the electron spin diffusion constant in MoSe2. [ABSTRACT FROM AUTHOR]

An incommensurate spin-density wave (Q phase) confined inside the superconducting state at high basal plane magnetic field is an unique property of the heavy-fermion metal CeCoIn5. The neutron scattering experiments and the theoretical studies point out that this state come out from the soft mode condensation of magnetic resonance excitations. We show that the fixation of direction of antiferromagnetic modulations by a magnetic field reported by Gerber et al. [Nat. Phys. 10, 126 (2014)], is explained by spin-orbit coupling. This result, obtained on the basis of quite general phenomenological arguments, is supported by the microscopic derivation of the Xzz susceptibility dependence on the mutual orientation of the basal plane magnetic field and the direction of modulation of spin polarization in a multiband metal. [ABSTRACT FROM AUTHOR]

The giant magnetoresistance (GMR) of a point contact between a Co/Cu multilayer and a superconductor tip varies for different bias voltage. Direct measurement of spin polarization by Andreev reflection spectroscopy reveals that the GMR change is due to a change in spin polarization. This work demonstrates that the GMR structure can be utilized as a spin source and that the spin polarization can be continuously controlled by using an external magnetic field. [ABSTRACT FROM AUTHOR]

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps). [ABSTRACT FROM AUTHOR]

We show spin torque oscillation at zero external magnetic field using a point-contact giant magnetoresistance device with a highly spin-polarized Co2Fe0.4Mn0.6Si (CFMS) Heusler alloy. The device emitted a high rf power (Prf) signal with a narrow spectral linewidth of 3 MHz without external magnetic field. Depending on the applied current, mode changes were clearly observed, and a large Prf of 25.7 nW was achieved. The large Prf and the high coherency of oscillation are attributable to the combination of the high spin-polarization of CFMS and the advantages of pointcontact geometry. [ABSTRACT FROM AUTHOR]

A theory of single-electron shuttling in an external magnetic field in nanoelectromechanical system with magnetic leads is presented. We consider partially spin-polarized electrons in the leads and electron transport in both the Coulomb blockade regime and in the limit of large bias voltages when the Coulomb blockade is lifted. The influence of the degree of spin polarization on shuttle instability is considered. It is shown that there is certain degree of spin polarization above which the magnetic field ceases to control electron transport. In the Coulomb blockade regime the dependence of the threshold magnetic field, which separates the "shuttle" and vibron regimes, on the degree of polarization is evaluated. The possibility of re-entrant transitions to the shuttle phase is discussed. [ABSTRACT FROM AUTHOR]

We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR [ABSTRACT FROM AUTHOR]

We present measurements of the electron transport in top-gated InAs spin-filter cascades. The cascades consist of a first filter stage that acts as a polarizer, a center wire, and a second filter stage that acts as an analyzer. Conductance quantization indicates quasi-ballistic transport in these rather large devices. Oscillations of the conductances of the second filter's outputs with the strength of an in-plane magnetic field perpendicular to the center wire provide evidence of the so-called zitterbewegung and substantiate the interpretation of the conductance imbalance at the second filter as the consequence of a spin polarization. [ABSTRACT FROM AUTHOR]

A compact optical electron polarimeter using a helium target is described. It offers a maximum fluorescence detection efficiency of ∼20 Hz/nA, which is an order of magnitude higher than that of earlier designs. With an argon target, this device is expected to have a polarimetric figure-of-merit of 270 Hz/nA. By relying on a magnetic field to guide a longitudinally spin-polarized electron beam, the present instrument employs fewer electrodes. It also uses a commercially available integrated photon counting module. These features allow it to occupy a smaller volume and make it easier to operate. [ABSTRACT FROM AUTHOR]

A quantum statistical description of the anomalous Hall effect is developed within the framework of the previously proposed thermodynamic mechanism of the anomalous Hall effect in weakly magnetic electron systems with spontaneous spin polarization. A qualitative explanation of the physical nature of the thermodynamic mechanism is followed by a general formulation of the quantum theory of the effect, based on accounting for the local-equilibrium currents. The behavior of the magnetic field dependences and quantum magnetic oscillations of the physical parameters characterizing the anomalous Hall effect is discussed. [ABSTRACT FROM AUTHOR]

The results of studies of the magnetic-field dependencies of the specific magnetization M(H) of a mercury selenide single crystal with a low concentration (0.01–0.035) at.% of cobalt impurities at a temperature of 5 K are presented. The contributions of the spontaneous magnetism of the electron system of hybridized states of donor impurity cobalt atoms, which have the form of magnetization curves with saturation, were revealed for the first time as a result of detailed precision analysis of the obtained experimental data. Certain magnetic parameters characterizing the spontaneous spin magnetism of the studied system agree with previous results obtained during observation of anomalies of the Hall effect and the temperature dependencies of the magnetic susceptibility associated with the manifestation of the same system. Therefore, in the present work, a solution to the problem of justifying and describing the spontaneous spin polarization of the electron systems of impurities of transition elements to the extent of their small concentration was developed in sufficient detail. [ABSTRACT FROM AUTHOR]

The anomalous Hall resistance relative with magnetic anisotropy of clusters Fe3Ga in Fe3Ga/Fe-Ga hybrid structural epitaxial was reported. The out-of-plane magnetic anisotropy was obtained for Fe3Ga/Fe-Ga hybrid structure, while in-plane magnetic anisotropy is shown in the single Fe-Ga phase epitaxial on GaAs(001). The observation of trend of saturation Hall resistance in Fe3Ga/Fe-Ga hybrid structural is compared with the Fe-Ga single crystal, which is solid evidence for spin polarization by local magnetic clusters. [ABSTRACT FROM AUTHOR]

We demonstrate a fast three-axis optical magnetometer using cold, optically trapped 87Rb gas as a sensor. By near-resonant Faraday rotation we record the free-induction decay of a spin polarized ensemble following optical to obtain the three field components and one gradient component. A single measurement achieves shot-noise limited sub-nT sensitivity in 1 ms, with transverse spatial resolution of ∼20 μm. We make a detailed analysis of the shot-noise-limited sensitivity. [ABSTRACT FROM AUTHOR]