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GaAs/AlGaAs core-shell nanowires, typically having 250 nm diameter and 6 mu m length, were grown on 2-inch Si wafers by the single process of molecular beam epitaxy using constituent Ga-induced self-catalysed vapor-liquid-solid growth. The growth was carried out without specific pre-treatment such as film deposition, patterning, and etching. The outermost Al-rich AlGaAs shells form a native oxide surface protection layer, which provides efficient passivation with elongated carrier lifetime. The 2-inch Si substrate sample exhibits a dark-colored feature due to the light absorption of the nanowires where the reflectance in the visible wavelengths is less than 2%. Homogeneous and optically luminescent and adsorptive GaAs-related core-shell nanowires were prepared over the wafer, showing the prospect for large-volume III-V heterostructure devices available with this approach as complementary device technologies for integration with silicon.

An exclusive advantage of semiconductor spintronics is its potential for opto-spintronics, which will allow integration of spin-based information processing/storage with photon-based information transfer/communications. Unfortunately, progress has so far been severely hampered by the failure to generate nearly fully spin-polarized charge carriers in semiconductors at room temperature. Here we demonstrate successful generation of conduction electron spin polarization exceeding 90% at room temperature without a magnetic field in a non-magnetic all-semiconductor nanostructure, which remains high even up to 110 degrees C. This is accomplished by remote spin filtering of InAs quantum-dot electrons via an adjacent tunnelling-coupled GaNAs spin filter. We further show that the quantum-dot electron spin can be remotely manipulated by spin control in the adjacent spin filter, paving the way for remote spin encoding and writing of quantum memory as well as for remote spin control of spin-photon interfaces. This work demonstrates the feasibility to implement opto-spintronic functionality in common semiconductor nanostructures. An electron spin polarization of 90% is achieved in a non-magnetic nanostructure at room temperature without magnetic field. This is accomplished by remote spin filtering of InAs quantum-dot electrons via an adjacent tunnelling-coupled GaNAs spin filter. Funding Agencies|Swedish Research CouncilSwedish Research CouncilEuropean Commission [2015-05532, 2019-04312, 201605091, 2020-04530]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [JA2014-5698]; Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; European Research Council, ERC AdG AMETISTEuropean Research Council (ERC) [695116]; Academy of FinlandAcademy of FinlandEuropean Commission [310985, 323989]; Japan Society for the Promotion of Science (JSPS)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [16H06359, 19H05507]; JSPSMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [19K15380]

A series of assembled PtII complexes comprising N-heterocyclic carbene and cyanide ligands was constructed using different substituent groups, [Pt(CN)2 (R-impy)] (R-impyH+ =1-alkyl-3-(2-pyridyl)-1H-imidazolium, R=Me (Pt-Me), Et (Pt-Et), i Pr (Pt-i Pr), and t Bu (Pt-t Bu)). All the complexes exhibited highly efficient photoluminescence with an emission quantum yield of 0.51-0.81 in the solid state at room temperature, originating from the triplet metal-metal-to-ligand charge transfer (3 MMLCT) state. Their emission colors cover the entire visible region from red for Pt-Me to blue for Pt-t Bu. Importantly, Pt-t Bu is the first example that exhibits blue 3 MMLCT emission. The 3 MMLCT emission was proved and characterized based on the temperature dependences of the crystal structures and emission properties. The wide-range color tuning of luminescence using the 3 MMLCT emission presents a new strategy of superfine control of the emission color.

An understanding of the spin-transport properties in semiconductor barriers is essential to improve the performance of spin-polarized light-emitting diodes (spin LEDs) for future optospintronics integration in information processing. Here, we report on the temperature and bias-voltage dependence of spin-transport properties in an ${\mathrm{In}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{As}$ quantum dot (QD) spin LED using a combination of spin-dependent electroluminescence (EL) and time-resolved photoluminescence. The QD EL spin polarization increases with an increase in temperature above 125 K; this is attributed to the improved conversion efficiency from spin polarization of electrons to circular polarization of photons of the QDs. We find that both the electric field and temperature can enhance spin relaxation in the undoped $\mathrm{Ga}\mathrm{As}$ barrier above 200 K. At 298 K, the QD EL spin polarization decreases beyond 2.5 V; this is attributed to the enhanced D'yakonov Perel' spin relaxation in the undoped $\mathrm{Ga}\mathrm{As}$ barrier caused by the increase in electron temperature. This study provides valuable insights into the spin-relaxation mechanism in the semiconductor barrier during the room-temperature operation of the QD spin LED.

We report on the enhancement effect of metal nanotriangles (NTs) on the photoluminescence and its time-resolved dynamics of tris(8-quinolinolato) aluminum (Alq3). Regularly arranged Al NTs arrays were fabricated on the quartz substrate by means of nanosphere lithography. The absorption peaks corresponded to the localized surface plasmon (LSP) resonance of Al NTs were observed within a visible light region, and it was significantly shifted towards longer wavelength as increasing refractive index of the covering medium. The typical resonance wavelength of LSP of Alq3/Al NTs fabricated with 350 nm-PSt beads was 600 nm. From the PL measurement 2.6-fold PL enhancement was observed in Alq3 with Al NTs at room temperature, whereas the 4.4-fold PL enhancement was observed for Ag NTs with same size. According to the time-resolved PL data, the coupling of LSP with the excitation light field mainly contribute to the observed emission enhancement for the Al NTs, whereas the emission enhancement by Ag NTs can be originated from the direct coupling of LSP and emission which was suggested from the large contribution of short lifetime component.

Electric-field-effect spin switching with an enhanced number of highly polarized electron and photon spins has been demonstrated using p-doped semiconductor quantum dots (QDs). Remote p-doping in InGaAs QDs tunnel-coupled with an InGaAs quantum well (QW) significantly increased the circularly polarized, thus electron-spin-polarized, photoluminescence intensity, depending on the electric-field-induced electron spin injection from the QW as a spin reservoir into the QDs. The spin polarity and polarization degree during this spin injection can be controlled by the direction and the strength of the electric field, where the spin direction can be reversed by excess electron spin injection into the QDs via spin scattering at the QD excited states. We found that the maximum degrees of both parallel and antiparallel spin polarization to the initial spin direction in the QW can be enhanced by p-doping. The doped holes without spin polarization can effectively contribute to this electric-field-effect spin switching after the initial electron spin injection selectively removes the parallel hole spins. The optimized p-doping induces fast spin reversals at the QD excited states with a moderate electric-field application, resulting in an efficient electric-field-driven antiparallel spin injection into the QD ground state. Further excess hole doping prevents this efficient spin reversal due to multiple electron-hole spin scattering, in addition to a spin-state filling effect at the QD excited states, during the spin injection from the QW into the QDs.

Trihexyltetradecylphosphonium (P-6,P-6,P-6,P-14) salts of luminescent anionic Pt(II) complexes, (P-6,P-6,P-6,P-14)[PtX2(ppy)] (X = Cl-, Br-; ppy = 2-phenylpyridinate), are synthesized and photofunctional thin films with crystal/liquid bi-stability are fabricated. In particular, the chloride complex provides a thin film exhibiting thermo- and mechano-triggered luminescence ON/OFF switching at ambient temperature, which is based on the control of the supercooled liquid phase and bright luminescent crystalline phase. The photophysical properties of the complexes are investigated and compared with those of the bromide complex and tetra(n-butyl)ammonium salts of the complexes. Furthermore, detailed photophysical analysis reveals a large contribution of the charge-transfer character to the ligand-centered (3)pi pi* excited state, which results in intense phosphorescence in the crystal and high-contrast luminescence ON/OFF by the phase transition of the chloride complex.

While pericytes wrap around microvascular endothelial cells throughout the human body, their highest coverage rate is found in the brain. Brain pericytes actively contribute to various brain functions, including the development and stabilization of the blood-brain barrier (BBB), tissue regeneration, and brain inflammation. Accordingly, detailed characterization of the functional nature of brain pericytes is important for understanding the mechanistic basis of brain physiology and pathophysiology. Herein, we report on the development of a new human brain pericyte cell line, hereafter referred to as the human brain pericyte/conditionally immortalized clone 37 (HBPC/ci37). Developed via the cell conditionally immortalization method, these cells exhibited excellent proliferative ability at 33 °C. However, when cultured at 37 °C, HBPC/ci37 cells showed a differentiated phenotype that was marked by morphological alterations and increases in several pericyte-enriched marker mRNA levels, such as platelet-derived growth factor receptor β. It was also found that HBPC/ci37 cells possessed the facilitative ability of in vitro BBB formation and differentiation into a neuronal lineage. Furthermore, HBPC/ci37 cells exhibited the typical "reactive" features of brain pericytes in response to pro-inflammatory cytokines. To summarize, our results clearly demonstrate that HBPC/ci37 cells possess the ability to perform several key brain pericyte functions while also showing the capacity for extensive and continuous proliferation. Based on these findings, it can be expected that, as a unique human brain pericyte model, HBPC/ci37 cells have the potential to contribute to significant advances in the understanding of human brain pericyte physiology and pathophysiology.

We report on the spin-conserved electron transport to self-assembled InGaAs quantum dots (QDs) through GaAs/AlGaAs superlattice (SL) by circularly polarized time-resolved photoluminescence spectroscopy of the QD excited states with the selective excitation for the SL minibands. The spin transport properties largely depend on the AlGaAs barrier thickness of the SL. The SL with a thinner barrier demonstrates a quantum spin transport to QDs with highly conserving the electron-spin polarization during the transport process through the SL minibands.

We study effects of p-doping on excited spin dynamics of InGaAs quantum dots (QDs) by circularly polarized time-resolved photoluminescence (PL). At excited states of p-doped QDs, the circular polarization degree (CPD) values are twice higher than those of undoped QDs. We attribute this enhanced CPD at excited states to spin-selective energy relaxation from the excited states to ground state. This can be promoted by the suppression of state filling at the ground state, which is induced by the decrease of PL lifetime due to the resident hole population.

We study effects of growth temperature of a capping layer on optical spin properties of In 0.5 Ga 0.5 As quantum dots (QDs) by photoluminescence (PL) spectroscopy including behaviors of the degree of circular polarization (CPD). The PL energy of the ground state shifts to lower energy with decreasing capping growth temperature, which is due to the increase of In composition inside QDs. The temperature dependence of PL intensity from the QD excited states shows the larger thermal activation energy with decreasing capping growth temperature, indicating the suppression of thermal escape of electrons from QDs to barriers. In addition, we observe the lower-energy shift of the CPD spectral peak, associated with decreasing PL energy, where the high CPD values can assure the high quality of these QDs grown with various capping growth temperatures.

We demonstrate electric-field control of optical-spin injection from an In 0.1 Ga 0.9 As quantum well (QW) to p-doped In 0.5 Ga 0.5 As quantum dots (QDs), where spin-polarized electrons are optically generated in the QW and then injected into the QDs via tunneling. The injected spin polarization in the QDs is detected by circularly polarized photoluminescence. The results show that the spin polarization is a function of electric field applied across the layered QW-QD structure. Moreover, p-doping has a marked effect on the polarity and degree of the spin polarization, which can provide precise control of the spin injection to QDs by an electric field using this p-doped QD-QW system.

We study lateral electronic coupling among self-assembled In 0.5 Ga 0.5 As quantum dots (QDs), which is promoted by adjoining tunnel-coupled In 0.1 Ga 0.9 As quantum-well (QW) potentials. The resultant collective electron and its spin dynamics at the coupled excited states in the QDs, virtually via the QW potential, are revealed by means of spin-resolved transient photoluminescence (TRPL). These QD excited states spread over those hybrid nano-systems composed of the coupled QDs and QW, which are elucidated by wavefunction calculations and then comparted to the TRPL results. The existence of the adjoining QW can induce stronger coupling among QDs in the lateral direction, where thicker QWs make stronger inter-dot coupling. We observe that circularly polarized TRPL, reflecting the spin dynamics, is dynamical functions of spin-polarized electron transfer among the coupled QDs and discrete-state filling in the QDs as well as spin relaxation in individual QDs. As a result, temporally stable high spin polarizations higher than 60 % are achieved in the QDs, sustained by selective transfer of minority spins into lower-energy spin states.

Improved electron-photon spin conversion efficiency is a key component of technological platforms for optospintronics integration in information processing; this concept is based on optical devices trans-mitting and receiving spin information superimposed on light. Semiconductor quantum dots (QDs) are the most promising materials for optospintronic devices; however, in addition to their weak room-temperature luminescence, their electron-photon spin conversion efficiencies are lower than 50%. Here, we present semiconductor QDs embedded in quantum wells (QWs) containing quasi-QDs. The proposed semiconductor hybrid nanosystem with gradual quantum dimensionality reduction demonstrates luminescence one order of magnitude stronger than that of conventional QDs and an electron-photon spin conversion efficiency of almost 80% at room temperature. Optical characterization reveals that efficient carrier capture, suppressed depolarized-spin reinjection, and quasi-three-dimensional quantum confinements in the QWs facilitate the highly efficient electron-photon spin conversion. This study constitutes a significant advance towards the realization of QD-based spin-functional optical devices for electron-spin-based quantum information platforms.

Asymmetric spin relaxation induced by the residual electron spin in semiconductor quantum dots (QDs) adjacent to a superlattice (SL) was studied using spin- and time-resolved photoluminescence under the selective photoexcitation of the SL miniband states. Spin-polarized electrons were photoexcited in the SL barrier and then injected into the QDs through spin-conserving tunneling. The spin-polarized electron transport and the faster transport of the electrons as compared to the holes generate the residual majority electron spins in the QDs. A reversal of the optical spin polarity was observed at the ground state of the QDs, depending on the excitation powers. A rate equation analysis considering the individual spin-flip times between spin-split QD states indicates that the polarity reversal originates from the asymmetric spin-flip process at the excited state of the QDs. The asymmetric spin relaxation is associated with the selective relaxation of the spin-flipped electron and hole to the unoccupied ground state, which is induced by the existence of the residual majority electron spin at this state. In addition, we observed a clear recovery of the optical spin polarity by eliminating the existence of the residual electron spin through heavy p-doping. These findings are important to attain a fundamental understanding of the spin relaxation mechanism within the QDs and provide an insight into the manipulation of the optical spin polarity by controlling the residual electron spins in the QDs.

The suppression of a thermally excited electron-spin relaxation in InGaAs quantum dots (QDs) using p-doped capping layers toward enhanced room-temperature (RT) spin polarization has been demonstrated, in which the electron-spin polarization in QD excited states (ESs) was measured through time-resolved spin-dependent photoluminescence. We revealed that the p-doping of QDs can enhance the emission intensity of QD-ES by approximately twofold to threefold over a wide temperature range. An electron-spin relaxation time of 106 ps was observed at 293 K for p-doped QDs, which is approximately three times longer than the radiative lifetime of 36 ps, relative to the shorter electron-spin relaxation time of 71 ps for undoped QDs. The increased electron-spin lifetime was mainly attributed to the suppressed relaxation of the electron spin reinjected from the p-doped capping barrier after thermal escape from an ES, where the D'yakonov-Perel' spin relaxation in the barrier was potentially weakened through impurity scattering. These results suggest that InGaAs QDs with p-doped capping layers have a significant advantage for use in spin-functional optical active layers with a higher spin polarization toward RT.

It is essential to understand which mechanism of localized surface plasmon (LSP) emission enhancement is to be utilized when combining plasmonic metal nanostructures with an emissive material to produce an optoelectronic device. Herein, we report on the size dependence and time-resolved dynamics of photoluminescence (PL) enhancement using three sizes of aluminum nanotriangles (Al NTs) on emission by tris(8-hydroxyquinolinato)aluminum (Alq3) for elucidating its enhancement mechanism. Al nanostructures were fabricated using a nanosphere lithography technique. Two-dimensionally aligned polystyrene (PSt) beads with different diameters were used as mask templates for obtaining the Al NTs. The absorption peaks red-shifted with increasing Al NT size, and hence, were attributed to the LSP resonance. From PL of Alq3 with and without Al NTs, 2–3 fold PL enhancements were observed among the samples with different Al NTs sizes. The significant shortening of the PL lifetime was observed only in Alq3/Al NTs using Ps500, indicating the effective coupling of LSP of Al NTs and the emission, which is also evidenced from the overlapping the PL peak and the LSP absorption. In contrast, the PL emission enhancement due to LSP coupling with the absorption process of Alq3 was dominant in Alq3/Al NTs using Ps200, suggested from the similarity of the PL decay curve with that of bare Alq3, and the excitation energy matching with LSP resonance. From these observation, we can distinguish the LSP coupling process (absorption or emission) from the presence or absence of lifetime enhancement in the time-resolved PL measurements, offering a guideline for designing the optical devices incorporating the metal nanostructures.

The temperature dependence of interdot spin-transfer dynamics at laterally coupled excited states (ESs) in high-density InGaAs quantum dots (QDs) was studied using spin- and time-resolved photoluminescence spectroscopy. At low temperatures below 100 K, temporary suppression of electron-spin polarization decay due to selective relaxation of minority spins from emissive ESs to lower-energy states in neighboring QDs was observed. In the temperature range from 20 K to 140 K, thermal activation of electron spins from lower-energy QD states to higher-energy states via interdot transfer prevents the aforementioned selective relaxation of minority spins, leading to a faster decay of electron-spin polarization during light emission. At high temperatures above 140 K, reinjection of depolarized electron spins from barriers after thermal escape from QD ESs accelerates the further decay of the electron-spin polarization, wherein the electron spins can be activated via ladderlike interdot transfer. These findings indicate that the suppression of reinjection of electron spins from barriers in a high-density QD system is crucial for maintaining high electron-spin polarization during light emission at high temperatures. Published under license by AIP Publishing.

The optical spin properties of size-modulated quantum nanocolumns (QNCs), which are composed of 9 layers of vertically coupled InGaAs quantum dots (QDs), have been studied by circularly polarized time-resolved photoluminescence spectroscopy of QD excited states with barrier excitation. High spin polarization at the emissive state is one of the essential elements in the development of spin-functional optical devices. Coupling of QD excited states can enhance the spin polarization if only minority spins are effectively removed from the emissive excited states. In this study, size-modulated QNCs with the increasing size toward the upper layer were grown, and we revealed that the combination of QD size modulation and electron wavefunction coupling in the stacking direction can greatly enhance spin polarization during light emission from the smaller-sized QD layers. We observed a temporal spin amplification of more than 80% at coupled excited states. This enhancement is derived from the size-modulation-induced selective transfer of minority spins to the larger-sized QD layers, which have abundant excited states where electron spins are transferred. In addition, we found that QNCs can retain high spin polarization even at high excitation spin density. Our findings of spin amplification during light emission will provide QNC systems suitable for spin-functional optical devices.The optical spin properties of size-modulated quantum nanocolumns (QNCs), which are composed of 9 layers of vertically coupled InGaAs quantum dots (QDs), have been studied by circularly polarized time-resolved photoluminescence spectroscopy of QD excited states with barrier excitation. High spin polarization at the emissive state is one of the essential elements in the development of spin-functional optical devices. Coupling of QD excited states can enhance the spin polarization if only minority spins are effectively removed from the emissive excited states. In this study, size-modulated QNCs with the increasing size toward the upper layer were grown, and we revealed that the combination of QD size modulation and electron wavefunction coupling in the stacking direction can greatly enhance spin polarization during light emission from the smaller-sized QD layers. We observed a temporal spin amplification of more than 80% at coupled excited states. This enhancement is derived from the size-modulation-induced...

Electric field control of spin polarity in spin injection into InGaAs quantum dots (QDs) from a tunnel-coupled quantum well (QW) was studied. The degree of freedom of the spin state in high-density QDs will play an important role in semiconductor spintronics such as a spin-functional optical device, where it is crucial to establish spin injection and manipulation by electric fields. To solve this subject in a layered device structure, electric field effects on spin injection from a 2-dimensional QW into 0-dimensional QDs were studied. Spin-polarized electrons were photo-excited in a QW and then injected into QDs via spin-conserving tunneling. After the injection, parallel spin states to the initial spin direction in the spin reservoir of QW were observed in QDs as a result of efficient spin injection, by circularly polarized photoluminescence indicating spin states in the QDs. Moreover, reversal of spin polarity was clearly observed at QD ground states, depending on the electric fields applied along the QD-QW growth direction. The tunneling rate of an electron is different from that of a hole and largely depends on the electric field, owing to electric field induced modifications of the coupled QD-QW potential. This results in negative trions in the QDs with anti-parallel spins to the initial ones in the QW, which is evidently supported by a significant effect of p-doping. The polarization degrees of both spin polarities can be optimized by excitation-spin density, in addition to the electric field strength.

Spin transport properties from the GaAs/AlGaAs superlattice (SL) to InGaAs quantum dots (QDs) are studied by circularly polarized time-resolved photoluminescence spectroscopy of QD excited states with the selective excitation of SL miniband states. For the SL with a thinner barrier, we observe an effective carrier transport in SL owing to the stronger overlap of wavefunctions of adjacent quantum wells and a simultaneous highly efficient carrier injection into QDs. Moreover, the SL with a thinner barrier demonstrates a quantum spin transport to QDs maintaining high spin polarization during the transport process.

Interdot carrier and spin dynamics were studied in a two-dimensional array of high-density small quantum dots (SQDs) of InGaAs with an average diameter of 16 nm and a sheet density of 1.2 x 10(11) cm(-2), in which 24 nm diametric large QDs (LQDs) were embedded as local potential minima. We observed a delayed photoluminescence (PL) rise from the lower-lying LQD states and a considerably faster PL decay from the higher-lying SQD states, indicating carrier transfer from the two-dimensionally coupled SQDs into the LQDs. In addition, inverse carrier tunneling from the LQDs into the SQDs was thermally induced, which is characterized by the thermal activation energy between the LQDs and SQDs. Moreover, circularly polarized transient PL behavior from the SQD states exhibits a suppression of the spin polarization decay in the initial time region, depending on the excited spin density. This tentatively suppressed spin relaxation can be quantitatively explained by selective interdot transfer of minority-spin electrons from the SQDs into LQDs, when the majority spin states in both QDs are sufficiently populated by excited spins. These findings indicate that the high-density SQDs behave as the main emitters with suppressed spin relaxation, while the scattered LQDs with lower potential behave as the receivers of minority-spin electrons.

Summary Our knowledge is limited regarding mechanisms by which transposable elements control host gene expression. Two Antirrhinum lines, HAM2 and HAM5, show different petal colors, pale-red and white, respectively, although these lines contain the same insertion of transposon Tam3 in the promoter region of the nivea (niv) locus encoding chalcone synthase. Among 1000 progeny from HAM5 grown under the preferred conditions for the Tam3 transposition, a few showed an intermediate petal color between HAM2 and HAM5. Transposon tagging using these progeny identified a causative insertion of Tam3 for the HAM5 type (white) petal color, which was found 1.6 kb downstream of the niv gene. Insertion of Tam3 at the position 1.6 kb downstream of niv alone showed nearly wildtype petal pigmentation, and the niv expression reduced by only 50%. Severe suppression of niv observed in HAM5 required interaction of two Tam3 copies on either side of the niv coding sequence. DNA methylation and small interfering RNAs (siRNAs) were not associated with the suppression of niv expression in HAM5. Insertion of a pair of transposons in close proximity can interfere with the expression of gene located between the two copies, and also provide evidence that this interference is not directly associated with pathways mediated by siRNAs.

Soybean dwarf virus (SbDV) causes serious dwarfing, yellowing and sterility in soybean (Glycine max). The soybean cv. Adams is tolerant to SbDV infection in the field and exhibits antibiosis to foxglove aphid (Aulacorthum solani), which transmits SbDV. This antibiosis (termed “aphid resistance”) is required for tolerance to SbDV in the field in segregated progenies of Adams. A major quantitative trait locus, Raso1, is reported for foxglove aphid resistance. Our objectives were to fine map Raso1 and to reveal whether Raso1 alone is sufficient to confer both aphid resistance and SbDV tolerance. We introduced Raso1 into cv. Toyomusume by backcrossing and investigated the degree of aphid antibiosis to foxglove aphid and the degree of tolerance to SbDV in the field. All Raso1-introduced backcross lines showed aphid resistance. Interestingly, only one Raso1-introduced backcross line (TM-1386) showed tolerance to SbDV in the field. The results demonstrated Raso1 alone is sufficient to confer aphid resistance but insufficient for SbDV tolerance. Tolerance to SbDV was indicated to require additional gene(s) to Raso1. Additionally, Raso1 was mapped to a 63-kb interval on chromosome 3 of the Williams 82 sequence assembly (Glyma1). This interval includes a nucleotide-binding site–leucine-rich repeat encoding gene and two other genes in the Williams 82 soybean genome sequence.

We demonstrate persistent high degrees of spin polarization (SPD) up to 70% during light emission in (In1-xGax) As quantum-dot-well (QD-QW) hybrid nanosystems, where QD excited states are laterally tunnel coupled through the adjacent two-dimensional QW potential depending on the QW thickness. Spinpolarized electrons are photo-excited by using circularly polarized light pulses. The decay time of spin relaxation, obtained by that of the SPD, is 70 times larger than the photoluminescence decay time. The temporally constant SPD is sustained by a selective transfer of minority spins among QDs after flipping from the majority spins, which is promoted by a moderate state filling of lower-energy spin sublevels in surrounding QDs. The spin transfer times are deduced as functions of the QW thickness and excited-spin density. These results can provide a precise control of lateral interdot spin-transfer dynamics and resultant suppression of spin relaxation in QD ensembles.

Interdot spin transfer dynamics is studied in a laterally coupled excited spin ensemble of high-density InGaAs quantum dots (QDs). We observe a rise time of the photoluminescence intensity of ∼100 ps and a simultaneous increase in the spin polarization of the excited spin ensemble, indicating spin injection from higher-energy levels in smaller QDs. Moreover, this coupled ensemble exhibits decay properties of the spin polarization that vary with the excited spin density. This phenomenon can be quantitatively understood by considering interdot spin transfer into lower-energy levels of the surrounding QDs, where the transfer rate depends on the degree of state filling of each QD level.Interdot spin transfer dynamics is studied in a laterally coupled excited spin ensemble of high-density InGaAs quantum dots (QDs). We observe a rise time of the photoluminescence intensity of ∼100 ps and a simultaneous increase in the spin polarization of the excited spin ensemble, indicating spin injection from higher-energy levels in smaller QDs. Moreover, this coupled ensemble exhibits decay properties of the spin polarization that vary with the excited spin density. This phenomenon can be quantitatively understood by considering interdot spin transfer into lower-energy levels of the surrounding QDs, where the transfer rate depends on the degree of state filling of each QD level.

In this study, we characterized Fe3O4(001) films using scanning tunneling microscopy/spectroscopy (STM/STS). On the film surfaces, individual iron atoms and ()R45° reconstructed structures were observed by STM. The STS results showed that the local density of states just below the Fermi level was higher in narrow sections than in wide sections of the surface reconstruction perpendicular to the iron rows. Periodic density of states modulations reproducing this electronic structure were clearly observed in the differential tunneling conductance map. These experimental results revealed the presence of subsurface charge ordering of Fe2+–Fe2+ and Fe3+–Fe3+ dimers, as proposed in previous density functional theory studies.

We report two types of adsorption structures in H/Fe3O4(001) film surfaces and the correlation between OH density and Fe electronic states, which have been studied by scanning tunneling microscopy/spectroscopy (STM/STS). Two types of bright protrusions (BPs), whose lengths along the atomic rows are different, are observed in the STM images. The shorter and longer BPs consist of Fe atoms with one and with two OH groups neighbor, respectively. In addition, STS measurements show the higher local density of states (LDOS) just below the Fermi level of Fe atoms with increasing neighboring OH groups. The variation can be attributed to the difference in the gain of electrons from H atoms, which is due to the difference in the number of neighboring OH groups. These results reveal that surface OH density is a factor for determining the LDOS just below the Fermi level of surface Fe atoms.

Fe3O4 is one of the important oxide materials and its surface structure should be well understood to enable application of this material. We report the first noncontact atomic force microscopy (NC-AFM) results for Fe3O4(001) thin films. The observed films were grown homoepitaxially on magnetite thin films substrate. A low-energy electron diffraction pattern shows the well-known (√2×√2)R45° reconstructed structure. The observed minimum step height is 0.21 nm, corresponding to the distance between the same planes. We obtain two types of atomic-scale NC-AFM images. One image shows bright protrusions along the [100] and [010] directions at intervals of 0.84 nm corresponding to a unit cell of the (√2×√2)R45° reconstructed structure. The other image shows a more detailed atomic structure with 0.6 and 0.3 nm corrugations.

We have studied the surface atomic configurations around antiphase domain boundaries (APBs) in epitaxial magnetite (Fe3O4) thin films on MgO(001) by scanning tunneling microscopy (STM). The observed surface of the Fe3O4 films is the B-plane terminating surface with the (√2×√2)R45° reconstruction. Several variations of APBs are observed by STM at atomic resolution. The observed APBs are categorized into a APBs labeled by three different phase shift vectors: in-plane 1/4[110], in-plane 1/2[100], and out-of-plane 1/4[101]. We discussed how these APBs appear on the surface. The proportions of the APBs with 1/4[110], 1/2[100], and 1/4[101] shifts are about 38, 1, and 61%, respectively, in our experiment.