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The helicity-dependent photoconductance of the edge states in three-dimensional topological insulator Bi$_2$Te$_3$ films was investigated. It was revealed that the helicity-dependent photoconductivity current on the left edge of the Bi$_2$Te$_3$ film showed an opposite sign with that on the right edge. Besides, the helicity-dependent photoconductivity current increased linearly with the applied longitudinal electric field, and it reversed the sign as the reversal of the electric field. As the thickness of the Bi$_2$Te$_3$ film increased, the helicity-dependent photoconductivity current also increased. Theoretical analysis suggested that the helicity-dependent photo-conductivity current may come from the intrinsic spin orbit coupling (SOC) or the SOC introduced by the chiral impurities or defects.

A persistent spin helix with equal strength of the Rashba and Dresselhaus spin-orbit coupling (SOC) is expected for future spintronic devices due to the suppression of spin relaxation. In this work we investigate the optical tuning of the Rashba and Dresselhaus SOC by monitoring the spin-galvanic effect (SGE) in a GaAs/Al0.3Ga0.7As two dimensional electron gas. An extra control light above the bandgap of the barrier is introduced to tune the SGE excited by a circularly polarized light below the bandgap of GaAs. We observe different tunability of the Rashba- and Dresselhaus-related SGE currents and extract the ratio of the Rashba and Dresselhaus coefficients. It decreases monotonously with the power of the control light and reaches a particular value of ∼−1, implying the formation of the inverse persistent spin helix state. By analyzing the optical tuning process phenomenologically and microscopically, we reveal greater optical tunability of the Rashba SOC than that of the Dresselhaus SOC.

Human lymphocytes as well as zebrafish embryos were used to study the toxicity of acrylamide, and the intervention effects of the dietary antioxidants (-)-epigallocatechin gallate and curcumin have...

The photoinduced inverse spin Hall effect (PISHE) has been studied in three dimensional (3D) topological insulator (TI) Bi

The circular photogalvanic effect (CPGE) provides a method utilizing circularly polarized light to control spin photocurrent and will also lead to novel opto-spintronic devices. The CPGE of three-dimensional topological insulator Bi2Te3 with different substrates and thicknesses has been systematically investigated. It is found that the CPGE current can be dramatically tuned by adopting different substrates. The CPGE current of the Bi2Te3 films on Si substrates are more than two orders larger than that on SrTiO3 substrates when illuminated by 1064 nm light, which can be attributed to the modulation effect due to the spin injection from Si substrate to Bi2Te3 films, larger light absorption coefficient, and stronger inequivalence between the top and bottom surface states for Bi2Te3 films grown on Si substrates. The excitation power dependence of the CPGE current of Bi2Te3 films on Si substrates shows a saturation at high power especially for thicker samples, whereas that on SrTiO3 substrates almost linearly increases with excitation power. Temperature dependence of the CPGE current of Bi2Te3 films on Si substrates first increases and then decreases with decreasing temperature, whereas that on SrTiO3 substrates changes monotonously with temperature. These interesting phenomena of the CPGE current of Bi2Te3 films on Si substrates are related to the spin injection from Si substrates to Bi2Te3 films. Our work not only intrigues new physics but also provides a method to effectively manipulate the helicity-dependent photocurrent via spin injection.

Background The aim of this study was to construct a model based on the prognostic features associated with epithelial–mesenchymal transition (EMT) to explore the various mechanisms and therapeutic strategies available for the treatment of metastasis and invasion by hepatocellular carcinoma (HCC) cells. Methods EMT-associated genes were identified, and their molecular subtypes were determined by consistent clustering analysis. The differentially expressed genes (DEGs) among the molecular subtypes were ascertained using the limma package and they were subjected to functional enrichment analysis. The immune cell scores of the molecular subtypes were evaluated using ESTIMATE, MCPcounter, and GSCA packages of R. A multi-gene prognostic model was constructed using lasso regression, and the immunotherapeutic effects of the model were analyzed using the Imvigor210 cohort. In addition, immunohistochemical analysis was performed on a cohort of HCC tissue to validate gene expression. Results Based on the 59 EMT-associated genes identified, the 365—liver hepatocellular carcinoma (LIHC) samples were divided into two subtypes, C1 and C2. The C1 subtype mostly showed poor prognosis, had higher immune scores compared to the C2 subtype, and showed greater correlation with pathways of tumor progression. A four-gene signature construct was fabricated based on the 1130 DEGs among the subtypes. The construct was highly robust and showed stable predictive efficacy when validated using datasets from different platforms (HCCDB18 and GSE14520). Additionally, compared to currently existing models, our model demonstrated better performance. The results of the immunotherapy cohort showed that patients in the low-risk group have a better immune response, leading to a better patient’s prognosis. Immunohistochemical analysis revealed that the expression levels of the FTCD, PON1, and TMEM45A were significantly over-expressed in 41 normal samples compared to HCC samples, while that of the G6PD was significantly over-expressed in cancerous tissues. Conclusions The four-gene signature construct fabricated based on the EMT-associated genes provides valuable information to further study the pathogenesis and clinical management of HCC.

CD8 + T lymphocytes are immune cells that play a crucial anti-tumor role in the human body, and prognostic value of CD8 + T cell-related regulatory genes in PAAD remains elusive. Data on 179 expression profiles across 13 immune cell datasets were downloaded from the GEO database, and the expression profiles of CD8 + T cell-related genes were obtained using WGCNA. Molecular subtypes based on CD8 + T cell-related genes were constructed using the ConsensusClusterPlus algorithm. Lasso regression analysis was performed to build a 10-gene signature. GSVA was performed to explore the pathways related to these ten genes. The IMvigor210 cohort was used to explore the predictive efficacy of the signature in terms of immunotherapy response. Four hundred and forty-six CD8 + T cell-related genes were obtained. One hundred and nine genes in TCGA and GEO datasets were closely related to the prognosis of patients and were included in the next study. PAAD samples were divided into two subtypes (IC1 and IC2) according to consensus cluster analysis. These two immune subtypes were significantly different in terms of immune checkpoint genes, immune function, and drug treatment response. Additionally, the 10-gene signature constructed based on CD8 + T cell-related genes showed a stable prognostic performance in TCGA and GEO cohorts. Moreover, it served as an independent prognostic factor for patients with PAAD. Furthermore, the 10-gene signature could effectively predict the response to immunotherapy. The immunophenotyping-derived prognostic model based on CD8 T cell-related genes provides a basis for the clinical treatment of pancreatic cancer.

Current-induced spin polarization (CISP) in the topological insulator (TI) ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ has been observed via circularly polarized photoconductive differential current (CPDC). It is found that the CPDC induced by the CISP is proportional to the square of the longitudinal electric field when the electric field is weak. The intensity of the CPDC decreases and finally reverses the sign when the thickness of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ films is increased from 3 to 20 QL, owing to the switching of the dominant contribution to the CPDC from the top surface states to the bottom surface states. The spin polarization degree (SPD) of the photoconduction and the critical electric field ${E}_{c}$ at which the SPD becomes saturated are determined, and it is revealed that the SPD decreases while ${E}_{c}$ increases with the increasing of the thickness of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ films. In addition, it is demonstrated that the CPDC excited by 1064 nm is more than one order larger than that excited by 1342 nm light, which is due to the larger optical absorption coefficient when excited by 1064 nm light. The temperature dependence of the CPDC and SPD of ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ films is also investigated, and it is found that the SPD induced by CISP first increases and then decreases with decreasing temperature. This work proposes a method using CPDC to investigate the CISP of TIs.

Although ternary polymer solar cells have more potential in realizing a high power conversion efficiency than the binary counterparts, the mechanism of exciton separation and charge transport in such complicated ternary systems is far from being understood. Herein, we focus on this issue and give a clear view on the detailed roles of the ternary components contributing to the device performance, through utilizing the technique of pump-probe photoconductivity spectroscopy combined with transient photoluminescence spectroscopy, for the first time for ternary polymer solar cells. The ternary photovoltaic devices are based on PBDB-T:ITIC:PC71BM and present a dramatic improvement in efficiency in comparison to that of the binary counterparts. Systematic investigation reveals that the excitons generated in ITIC could be separated at the interface of PBDB-T:ITIC rather than ITIC:PC71BM with holes injecting to PBDB-T. These holes together with those generated in PBDB-T contribute to the photocurrent of the devices. The aggregation of holes in PBDB-T would also weaken the exciton generation herein, and the electron injection to PC71BM and ITIC would also be influenced. The key role of PC71BM in the ternary devices is accepting the electrons from PBDB-T and transporting them to the cathode with a higher rate than that of ITIC. Thus, this article is of importance in constructing high-efficiency ternary polymer solar cells.

Circular photogalvanic effect (CPGE) of single-crystalline ternary topological insulator [Formula: see text] nanowires, which are synthesized by the chemical vapor deposition, have been investigated. It is demonstrated that the distributions of the elements in the nanowires are fairly uniform, and they have high crystal quality. Compared with [Formula: see text] nanowires, the ternary [Formula: see text] nanowires have better responsivity to circularly polarized light. The incident angle dependence of the CPGE current indicates that the symmetry of the surface states of the nanowire belongs to [Formula: see text] symmetry. The temperature dependence of the CPGE current is also investigated. As the temperature decreases from 300 to 77 K, the CPGE current first increases and then decreases, which is due to the variation of the mobility and photo-generated carrier density with temperature. Our work suggests that ternary [Formula: see text] nanowires are good candidates for designing polarization-sensitive photoelectric devices.

We have measured a helicity-dependent photocurrent at zero external magnetic field in a device based on a semiconductor quantum well embedded in a p-i-n junction. The device is excited under vertical incidence with circularly polarized light. The spin filtering effect is evidenced in the range 77–300 K at B = 0 owing to a CoFeB/MgO spin filter with out-of-plane magnetization in remanence. The helicity-dependent photocurrent is explored as a function of the temperature and bias. These characteristics are compared with those of a spin photocurrent device with in-plane magnetized CoFeB/MgO spin filter, excited under oblique incidence with circularly polarized light. In contrast to the in-plane spin filter device, the circularly polarized light asymmetry of the photocurrent in the out-of-plane device depends weakly on the external bias. This may be attributed to the large spin relaxation anisotropy in III-V zinc-blende quantum wells in the presence of a vertical electric field.

The photo-excited electrons and holes move in the same direction in the diffusion and in the opposite direction in the drift under an electric field. Therefore, the contribution to the inverse spin Hall current of photo-excited electrons and holes in the diffusion regime is different to that in the drift regime under electric field. By comparing the classical Hall effect with the inverse spin Hall effect in both diffusion and drift regime, we develop an optical method to distinguish the contributions of electrons and holes in the inverse spin Hall effect. It is found that the contribution of the inverse spin Hall effect of electrons and holes in an InGaAs/AlGaAs un-doped multiple quantum well is approximately equal at room temperature.

The circular photogalvanic effect (CPGE) provides a method utilizing circularly polarized light to control spin photocurrent and will also lead to novel opto-spintronic devices. The CPGE of three-dimensional topological insulator Bi

High power conversion efficiency can be realized by using a ternary bulk heterojunction with complementary absorption spectra in organic solar cells. However, as the development of nonfullerene acceptors with a broad absorption spectrum makes the absorption efficiency of the photovoltaic devices close to optimal, such a strategy needs modifying. In particular, charge transfer between the two acceptors is necessary to be considered. Herein, we purposely design a ternary system based on PTB7-Th:COi8DFIC:ITIC-4F. Though the presence of ITIC-4F in PTB7-Th:COi8DFIC could not broaden the absorption spectrum obviously, the formed cascade-energy-level alignment is beneficial for promoting and balancing exciton separation and charge transport between the donor and two acceptors and even between the acceptors. Insights into the charge transport route in the completed system are provided via using the techniques including photoluminescence spectroscopy and pump-probe photoconductivity spectroscopy. This work provides a new idea for designing highly efficient ternary organic solar cells.

International audience; We study the photogenerated spin currents in a spin light emitting diode when the device is excited under circularly polarized light. The device is based on a In 0 1 Ga 0 9 As quantum well embedded in a p-in junction. The spin filtering is performed owing to a Co-Fe-B/MgO electrode with out-of-plane magnetization. The helicity-dependent photocurrent is explored as a function of the incident and azimuth angles of the incoming light wave vector with respect to the magnetization direction of the ferromagnetic electrode. The results are interpreted as a simple phenomenological model described in the paper, which demonstrates it is an efficient way to detect the remanent < (remnant?) magnetic moment of the ferromagnetic electrode at room temperature.

The inverse spin Hall effect induced by circularly polarized light has been observed in a GaAs/AlGaAs two-dimensional electron gas. The spin transverse force has been determined by fitting the photo-induced inverse spin Hall effect (PISHE) current to a theoretical model. The PISHE current is also measured at different light power and different light spot profiles, and all the measurement results are in good agreement with the theoretical calculations. We also measure the PISHE current at different temperatures (i.e., from 77 to 300 K). The temperature dependence of the PISHE current indicates that the extrinsic mechanism plays a dominant role, which is further confirmed by the weak dependence of the PISHE current on the crystal orientation of the sample.

Linjun Hu,1,* Qinxin Zhao,2,* Hongsong Bai,1 Chengming Xie,1 Xingli Shan,1 Dehu Lu,1 Yonghai Chen,1 Dongdong Han,1 Zejun Xiao,2 Jun Tian,2 Dong Wang,2 Xingang Bi,2 Nianzeng Xing2 1Department of Urology, Cancer Hospital of HuanXing Chaoyang District Beijing, Beijing, People’s Republic of China; 2Department of Urology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Nianzeng XingDepartment of Urology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 17, Panjiayuan South Li, Beijing, Chaoyang 100021, People’s Republic of ChinaEmail xingnianzeng@hotmail.comPurpose: The aim of this study was to evaluate the efficacy and safety of hormonal and synchronous docetaxel plus prednisone (DocP) in metastatic hormone-sensitive prostate cancer (mHSPC).Methods: One hundred fifty-one cases with high-burden mHSPC diagnosed at 1 single center from January 2014 to August 2018 were analyzed retrospectively. Among them, 85 cases received androgen-deprivation therapy (ADT) within 3 months, along with 6 cycles of docetaxel + prednisone (treatment group), whereas 66 received ADT alone (control group). The primary end point was the median overall survival (OS), while the secondary outcomes included prostate-specific antigen (PSA) progression-free survival (PFS), radiographic PFS, and the proportion of PSA falling to 0.2 ng/mL.Results: A total of 151 patients were included and followed up for a median of 34 months in this study. The median OS time in the treatment group was unavailable, but it was remarkably longer than that of the control group (P< 0.001). In addition, the PFS of PSA in the treatment group and control group was 17.9 months and 9.2 months, respectively (P< 0.001). Meanwhile, the radiographic PFS was 43 months in the treatment group and 19.8 months in the control group, respectively (P< 0.001). The proportions of PSA falling to 0.2 ng/mL were 53.7% and 23.3%, respectively (P< 0.001). However, there was no significant difference in the incidence of ≥ 3 toxic side effects between these 2 groups (P=0. 21).Conclusion: ADT combined with 6 cycles of docetaxel + prednisone chemotherapy benefits patients diagnosed with high-burden mHSPC in terms of the OS, PFS of PSA and radiographic, and the ratio of PSA falling to 0.2 ng/mL.Keywords: androgen-deprivation therapy; ADT, docetaxel, high-burden, metastatic hormone-sensitive, prostate cancer;PCa

Helicity-dependent photocurrent (HDPC) has been observed in epitaxial thin films of the three-dimensional topological insulator ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$ with a thickness of 7, 20, and 30 quintuple layers (QLs). By analyzing the incident angle dependence of the HDPC, we successfully extract the photocurrent induced by the circular photon drag effect (CPDE) of even parity from the HDPC. It is found that the circular photogalvanic effect (CPGE) is larger than the odd parity of CPDE. The CPGEs of the top and bottom surface states are successfully distinguished at room temperature. As the thickness of the ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$ film is increased from 7 to 20 QLs, the dominant contribution of the CPGE current switches from the top surface states to the bottom surface states under the front illumination of a 1064-nm laser. Additionally, it is found that the CPGE currents of the 20- and 30-QL samples reverse sign when the temperature is increased from 77 to 300 K, which may be attributed to the HDPC current induced by the combined action of the inverse spin Hall effect and the vertical thermoelectric effect overwhelming the CPGE current at low temperature in the samples. The insights we obtained are significant for engineering optospintronic devices based on three-dimensional topological insulators with a strong thermoelectric effect.

Organic-inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, the optical bandgap of CH3NH3PbI3 perovskite is still disputed. In order to comprehend the intrinsic characteristics of these materials, we study the near-band-edge optical responses of the solution-processed CH3NH3PbI3 perovskite crystals by photoconductivity and reflectance spectroscopy at room temperature. All these spectra of the CH3NH3PbI3 polycrystals show only one significant absorption edge at 1.58 eV. However, we observe an extra absorption edge at 1.47 eV in CH3NH3PbI3 single crystal. We establish a simple kinetic model of charge annihilation processes to explain why the low-energy structure of the photoconductivity and diffuse reflectance spectra of CH3NH3PbI3 polycrystals disappear, which provides another possibility for understanding the difference in absorption edge. It is noteworthy that this low-energy absorption edge of CH3NH3PbI3 single crystal has, to the best of our knowledge, seldom been reported on organic-inorganic hybrid perovskites. Therefore, the CH3NH3PbI3 single crystal exhibits a relatively wide absorption which makes it a promising candidate for photoelectric applications.

Extensive efforts have been undertaken on the photoelectric physics of hybrid organolead halide perovskites to unveil the reason for the attractive photovoltaic performance. Yet, the resulting evidence is far from being fully conclusive. Herein, we provide another direct support for this issue. In addition to the observation on the conventional band edge at 1.58 eV that presents a blueshift toward temperature increase, interestingly, we also observe an unusual optical band edge at 1.48 eV in CH3NH3PbI3 perovskite single crystals for the first time. Contrary to the conventional band edge, this one shows an obvious redshift toward the enhancement in temperature, in agreement with the Varshni relation. More interestingly, the unusual band edge exhibits a series of obvious absorption and photocurrent signals, but the according photoluminescence signals are not observable. This indicates that this band edge is particularly beneficial for the photovoltaic effect due to the inhibited radiative recombination. The...

A hallmark signature of the three-dimensional (3D) topological insulator (TI) is that the spin-momentum locked massless Dirac fermions populate its surface states, where the carrier spins are locked to their momentum. Here, we report on the magnetic-field induced helicity dependent photogalvanic effect (MHPGE) of 3D TI thin films Bi 2Te 3 or (Bi xSb 1−x) 2Te 3 of different thicknesses excited by near-infrared (1064 nm) under an in-plane magnetic field. It is found that the MHPGE current Jcx under the longitudinal geometry, i.e., Jcx∥Bx, is induced by the Larmor procession, while that under the transverse geometry, i.e., Jcx∥By, is mainly introduced by the hexagonal warping, which can be enhanced by the in-plane magnetic field. Our work demonstrates the possibility to tune the spin-polarized photocurrent of the surface states in 3D TIs via a magnetic field, which may be utilized to design new kinds of opto-spintronic devices.

The three-dimensional (3D) topological insulator (TI) Bi2Se3 exhibits topologically protected, linearly dispersing Dirac surface states (SSs). To access the intriguing properties of these SSs, it is important to distinguish them from the coexisting two-dimensional electron gas (2DEG) on the surface. Here, we use circularly polarized light to induce the inverse spin Hall effect in a Bi2Se3 thin film at different temperatures (i.e., from 77 to 300 K). It is demonstrated that the photoinduced inverse spin Hall effect (PISHE) of the top SSs and the 2DEG can be separated based on their opposite signs. The temperature and power dependence of the PISHE also confirms our method. Furthermore, it is found that the PISHE in the 2DEG is dominated by the extrinsic mechanism, as revealed by the temperature dependence of the PISHE.

(110)SrTiO3:Nb (NSTO)/ZnO heterojunctions were fabricated by magnetron sputtering. The NSTO/ZnO heterojunctions exhibit a typical rectification characteristic, and two attendant behaviors of bipolar resistive switching and negative differential resistance appear after applying a magnetic field. The ideality factor (n) increases from 3.0 to 8.8 and the density of interface state Nss increases from 8.4×1013 to 1.8×1014 eV−1·cm−2 after applying a magnetic field. The variance of interface state density can be used to qualitatively understand the above results.

(100)Nb:SrTiO 3 /(110)ZnO heterojunction were epitaxially grown by RF magnetron sputtering. A typical rectification characteristic was observed before and after applying a magnetic field, but the rectifying effect was significantly enhanced after applying a magnetic field. From high and low frequency capacitance-voltage measurement, the interface state density is found to increase from 3.8 × 10 12 to 8.2 × 10 12 eV −1 cm −2 after applying a magnetic field of 0.55 T at room temperature. Furthermore, both the rectification ratio and interface state density increase after applying a magnetic field at temperatures from 90 to 300 K. The magnetic field enhanced rectifying effect can be understood by the increase of interface state density. This result is promising for magnetoelectric applications.

The photocurrent spectra induced by the anomalous Hall effect (AHE) of the (001)-oriented GaAs/AlGaAs quantum wells (QWs) with well width of 3 and 7 nm have been investigated at room temperature. Ultra-thin InAs layers with a thickness of 1 monolayer have been inserted at GaAs/AlGaAs interfaces to tune the asymmetry of the QWs. It is demonstrated that the AHE current can be effectively tuned by the inserted ultra-thin InAs layers and by the well width. A method has been proposed to separate the intrinsic and extrinsic mechanisms of the AHE, which can be also applied to spin Hall effect.

International audience; We have measured a helicity-dependent photocurrent at zero external magnetic field in a device based on a semiconductor quantum well embedded in a p-in junction. The device is excited under vertical incidence with circularly polarized light. The spin filtering effect is evidenced in the temperature range 77-300 K owing to a CoFeB/MgO spin filter with out-of-plane magnetization in remanence. The helicity-dependent photocurrent is explored as a function of the temperature and bias. These characteristics are compared with those of a spin photocurrent device with in-plane magnetized CoFeB/MgO spin filter, excited under oblique incidence with circularly polarized light. In contrast to the in-plane spin filter device, the circularly polarized light asymmetry of the photocurrent in the out-of-plane device depends weakly on the external bias. The two devices are sensitive to the spin filtering of either the in-plane (S x) or out-of-plane (S z) photogenerated electron spin in the semiconductor quantum well. The helicity-dependent photocurrent results can be explained by the Dyakonov-Perel electron spin-relaxation mechanism. Our study reveals the giant spin relaxation anisotropy in III-V zinc-blende quantum wells in the presence of a vertical electric field.

The anomalous circular photogalvanic effect (ACPGE) is observed in p-GaAs with a thickness of 2 μm at room temperature, in which circularly polarized light is used to inject spin-polarized carriers and the spin diffusion can generate a macroscopic detectable charge current due to the inverse spin Hall effect. The normalized ACPGE signals show first increasing and then decreasing with increasing the doping concentration. The role of the doping impurities is discussed by both extrinsic and intrinsic models, and both can well explain the variation of ACPGE with the doping concentration.

Ultra-thin Bi 2Se 3 nanoplates with high crystal quality are obtained by chemical vapor deposition (CVD). A giant circular photogalvanic effect (CPGE) has been observed in the ultra-thin Bi 2Se 3 nanoplates, which is about one order larger than that previously observed in the thick Bi 2Se 3 nanoplates grown by CVD and that in the thin Bi 2Se 3 film grown by molecular beam epitaxy. By applying an ionic liquid gate, the CPGE can be effectively tuned. As the gate voltage increases, the magnitude of the CPGE current decreases, suggesting that the CPGE current under zero gate voltage is dominated by surface states rather than the two-dimensional electron gas (2DEG). It is revealed that as the surface roughness of the Bi 2Se 3 nanoplates increases, the CPGE decreases and finally reverses the sign, indicating the dominant contribution of the CPGE switches from the top surface states to the 2DEG or the bottom surface states.

An ultra-thin InAs layer with a thickness of 1 monolayer (ML) has been inserted at the direct (AlGaAs-on-GaAs) and inverted (GaAs-on-AlGaAs) interfaces in (001)-grown GaAs/AlGaAs quantum wells (QWs) with different well widths varying from 2 to 14 nm, respectively. The in-plane optical anisotropy (IPOA) of these samples are investigated by reflectance difference spectroscopy. It is demonstrated that the IPOA of the QW sample with the ultra-thin InAs layer inserted at the direct interface is larger than that with InAs layer inserted at the inverted interface, which can be attributed to the smaller segregation effect of indium atoms at the direct interface compared to that at the inverted interface as confirmed by theoretical calculations based on 6 band k · p theory. Our results demonstrate that indium atoms present different segregation lengths at the direct and inverted interfaces of GaAs/AlGaAs QWs.

Circularly polarized photocurrent is observed in few-layer MoTe2 at room temperature. The spatial distribution of the circularly polarized photocurrent exhibits the characteristics of two wings, one positive and the other negative, not only in the middle of the sample but also near the electrodes. In addition, the circularly polarized photocurrent signal in the middle of the sample is opposite to the signal near the electrode at the same side. It is revealed that this phenomenon arises from the inverse spin Hall effect of spin-polarized photo-generated carriers, which is dominated by the carrier diffusion or the carrier drift depending upon the location of the light spot.

Topological insulators (TIs) are considered as ideal spintronic materials due to the spin-momentum-locked Dirac surface states. The photoinduced anomalous Hall effect (PAHE) is a powerful tool to investigate the spin Hall effect of topological insulators even at room temperature. In this Letter, the PAHE has been observed in three dimensional topological insulator Bi2Te3 thin films grown on Si substrates at room temperature. As the thickness of the Bi2Te3 films increases from 3 to 20 quintuple layer (QL), the PAHE first increases and then decreases, and it reaches a maximum at 7 QL. The sign reversal of the PAHE of the 3 QL sample after oxidation reveals that the PAHE of the Bi2Te3 thin films is dominated by the top surface states, which is further confirmed by the circular photogalvanic effect under front and back illuminations. The photoinduced anomalous Hall conductivity excited by 1064 nm light is as large as 5.28 nA V−1 W−1 cm2 in the 7 QL sample, much larger than that observed in InGaAs/AlGaAs quantum wells (0.445 nA V−1 W−1 cm2) and GaN/AlGaN heterostructures (0.143 nA V−1 W−1 cm2). By comparing the PAHE current excited by 1064 nm with that excited by 1342 nm, we reveal that the tremendous PAHE excited by 1064 nm light is due to the modulation effect of spin injection from Si substrates. The giant PAHE value observed in TI Bi2Te3 may offer spintronic applications of TIs such as high-efficient light-polarization-state detectors.

Recent advances in ternary organic solar cells (OSCs) based on O6T-4F have revealed the attractive potential of O6T-4F in developing highly efficient devices. Even so, the exploration of photocurrent generation mechanisms in O6T-4F based devices remains critical and challenging. In this study, we systematically research on exciton separation and charge transport route in ternary OSCs based on PTB7-Th: O6T-4F: PC71BM by novel pump-probe photoconductive (PC) spectroscopy. Detailed studies suggest that, benefiting from the superior molecular structure, O6T-4F plays a dominant role in the photocurrent generating and charge transport. The electron injection rate from the donor to O6T-4F is fivefold larger than PC71BM. The separation of exciton of O6T-4F mainly occurs on the interface with the donor and that at the interface with PC71BM is ignorable. Moreover, for extracting electrons efficiently, a self-assemble monolayer (SAM) of 4-aminobenzoic acid (ABA) is used to modify the ZnO electron transport layer. The optimized ternary OSCs achieve a striking improvement in short-circuit current density (Jsc) and efficiency. This work provides a perspective of viewing the relationship between two acceptors in ternary system and an effective strategy to improve charge transport at the interface.

Asymmetric resistive switching processes were observed in BaTiO3/Nb:SrTiO3 epitaxial heterojunctions. The SET switching time from the high-resistance state to low-resistance state is in the range of 10 ns under + 8 V bias, while the RESET switching time from the low-resistance state to high-resistance state is in the range of 105 ns under − 8 V bias. The ferroelectric polarization screening controlled by electrons and oxygen vacancies at the BaTiO3/Nb:SrTiO3 heterointerface is proposed to understand this switching time difference. This switch with fast SET and slow RESET transition may have potential applications in some special regions.

The inverse spin Hall effect (ISHE) induced by the normal incidence of linearly-polarized infrared radiation has been observed in the topological insulator Bi