The coupling of valley and spin degrees of freedom in 2D materials holds significant promise for advancing novel device applications. In this study, a highly polarized spin-valley transistor based on the circular dichroic photocurrent in WS2 is demonstrated. By integrating highly spin-selective tunneling spin detectors and leveraging the magnetic proximity effect of spin-polarized substrates, the spin degeneracy in optical transition and spin transport can be broken. A giant photocurrent polarization of 41.90% is realized at room temperature under ultraviolet light irradiation. Interestingly, the sign of the circular dichroism can be reversed by switching the magnetization of substrates and electrodes, showing an opposite resistance state under circularly polarized light. This device has removed the hurdle for developing complementary phototransistors (as they are always in low-resistance states under light illumination), which are further exploited to construct reconfigurable logic gates. The findings will pave the way for new developments in optical couplers and on-chip optical computing technologies.

The combination of antiferromagnetism and topological properties in Mn3X (X = Sn,Ge,Ga) offers a unique platform to explore novel spin-dependent phenomena and develop innovative spintronic devices. Here, we have systematically investigated the phase transition of Mn3Ga thin films on SiO2(001)/Si substrates under various growth parameters such as seeding layer structure, annealing conditions, and film thickness. The relatively thick Mn3Ga films grown with Ru seeding exhibit a variety of polycrystalline hexagonal phases, including (002), and (201). The addition of a Ta layer to the conventional Ru seeding layer promotes the formation of nearly single-crystal antiferromagnetic (AF) Mn3Ga(002) phase from the relatively thin Mn3Ga films after annealing at 773 K. The investigation of the growth mechanism of Mn3Ga polycrystalline thin films provides a reference strategy for exploring Mn-based AF spintronic devices.

The manipulation of the Rashba effect in low‐dimensional systems is desirable for next generation spintronic devices. Herein, a novel strategy is proposed to regulate Rashba spin splitting through interfacial interaction in Janus WTeSe/InN heterostructures based on first‐principles calculations. Three kinds of WTeSe/InN heterostructures with different stacking interfaces are constructed, and the dependence of Rashba constant on the stacking configurations and the interfacial atoms is comprehensively investigated. The maximum Rashba constant of 1.55 eV Å −1 is achieved in the WTeSe/N‐terminated InN heterostructure, representing a 193% enhancement compared to pristine Janus WTeSe (0.53 eV Å −1 ). It is found that the enhanced Rashba effect is related not only to the net interfacial electric field but also to the interface elements (or interfacial coupling). Furthermore, the Rashba effect of WTeSe/N‐terminated InN heterostructure is regulated by interlayer distances and an external electric field. The Rashba constants increase to 1.95 and 1.74 eV Å −1 at an interlayer spacing of 2.1 Å and under an applied electric field of −0.3 V Å −1 , respectively, showing increases of 26% and 12%. This work paves a novel way to modify the Rashba effect in 2D semiconductors.

Two-dimensional heterojunctions with a type-II band alignment have great potential for high-performance optoelectronic devices due to their inherent carrier separation properties. Herein, we synthesized lateral and vertical MoS2/WS2 heterojunctions through a two-step chemical vapor deposition method and deeply investigated the impact of the interface structures on carrier separation efficiency. The experimental results demonstrate that the structures of MoS2/WS2 heterojunctions can be controlled by adjusting the Mo/S ratio. In addition, lateral heterojunctions exhibit a significantly higher carrier separation efficiency than vertical heterojunctions. Specifically, the interlayer charge transfer time in the lateral heterojunction is approximately 1.2 ps, in contrast to the value of about 4.0 ps in the vertical heterojunction. First-principles simulation reveals that the lateral heterojunction has stronger interface coupling and orbital hybridization, contributing to its faster charge transfer rate. This work demonstrates the superiority of lateral heterojunctions in carrier separation, offering valuable insights for high-performance optoelectronic devices.

The crystallization and magnetic properties strongly depend on the orbital coupling and spin polarization of magnetic materials. Here, the enhancement and freeze of coupling and polarization of atomic orbitals achieved by high magnetic fields are delineated through the first-principles calculations. Thus a growth method (under high magnetic fields) is proposed to design the crystallization and magnetic structure of the Fe/Pd thin films. The dynamic processes of film growth are revealed based on the observation of transmission electron microscopy. As the magnetic field increased, the Fe film is found to develop from a unique droplet shape to a 2D growth mode, which is caused by the competition between demagnetization energy and interfacial energy. Furthermore, the improvements achieved by high magnetic fields in macroscopic magnetic properties and ordered magnetic domains are demonstrated, confirming the effective regulation of the orbital coupling and spin textures from this designed method. This work provides a new perspective for understanding the interaction between atomic-orbital and external magnetic fields and offers a strategy for the preparation of high-performance magnetoelectric and spintronic devices.

The 2D materials are promising channel materials for spin transistors due to their natural spatial-confined carrier transport character. Nonetheless, electrical spin injection and detection in 2D semiconductors used to be challenging. This study reports high-efficient spin injection and transport in 2D GeSe, which exhibits moderate spin-orbit coupling (SOC) and extended spin diffusion lengths due to the van der Waals structure. The non-local magnetoresistance (MR) measurements show a maximum spin polarization of 18.31%, a long spin diffusion length of 255.98 nm, and a giant spin relaxation time of 17.6 ns at room-temperature. After cooling to 4.3 K, the elevated spin diffusion length further increases to 397.04 nm, with an elevated spin polarization of 25.38%, leading to the successful observation of local MR in a two-terminal lateral spin valve. Additionally, the spin transport characteristics are also tunable by gate voltages due to the field-dependent SOC and Rashba spin relaxation. This study highlights GeSe as an air-stable 2D semiconductor with anisotropic and gate-tunable spin transport capability. The results will remove the barriers to developing novel spintronic devices based on emerging 2D semiconductors.

Eutrophication and metal pollution threaten coastal ecosystems, yet interactions between these stressors are insufficiently explored. This study investigated how nitrogen (N) and copper (Cu) levels impact the physiology of the marine diatom Thalassiosira weissflogii. Results indicate that high nitrogen (HN) conditions significantly alleviate copper's inhibitory effects on chlorophyll a (Chl a) synthesis, growth rate (μ), and photosynthetic performance. Under low nitrogen (LN) conditions, high Cu exposure reduced Chl a content and growth rates by up to 72 % and 55 %, respectively, while reductions under HN were less severe (56 % for Chl a, 20 % for growth). Higher relative electron transport rate (rETR) and gross oxygen release by PS II (GO) under HN across Cu concentrations suggest that N enrichment buffers the toxicity of Cu on this diatom by potentially enhancing PSII activity. These findings underscore the role of nutrient-metal interactions in ecosystem management, highlighting how eutrophication may mitigate heavy metal stress in coastal waters.

Two-dimensional transition metal dichalcogenides represent a highly attractive platform for the development of valleytronic devices due to their unique spin-valley properties. Herein, a plasma-assisted interfacial engineering is proposed to enhance valley polarization and valley splitting in MoS2/AlN heterostructure by modifying the surface configurations of AlN substrates. The experimental results show that after the optimized N-2-plasma treatment, the AlN surface becomes smoother with a decreased migration barrier, thereby facilitating the growth of high-quality MoS2. The valley splitting and degree of valley polarization in the optimal sample reach 7.96 meV (the corresponding Land & eacute; g factor is 19.6) and 33.8% at -7 T, which are 16.0- and 1.0-fold higher than those in the untreated MoS2/AlN heterostructure, respectively. Theoretical simulations indicate that the enhanced spin-valley properties are predominantly ascribed to the AlN surface magnetism induced by the hybridization of P-z and P-y orbitals of surface N and O atoms. This work opens a new avenue for manipulating spin-valley properties in 2D materials via interfacial engineering.

The interplay between excitons and physical fields emerges as a forefront research topic within the domain of condensed matter physics, harboring significant impact for unraveling material properties. Herein, we investigate the valley exciton behaviors in Janus MoSeS/MoSe2 heterostructures with 2H- or 3R-stacking configurations. We ascertain that the intrinsic polarized electric field in Janus materials can markedly enhance the valley polarization. Furthermore, experimental results reveal that different excitons exhibit inequivalent spin-valley dynamic processes under intrinsic electric fields. Among them, intervalley trions exhibit a superior capability to preserve their spin states under a strong intrinsic electric field due to the quantum-confined Stark effect, thereby achieving the highest degree of valley polarization. This work provides fundamental insights into the strong correlation effect between excitons and polarized electric fields, signifying an advancement in control over the valley degree of freedom.

With the rapid development of the third-generation semiconductor materials, the chemical mechanical polishing rate and surface quality of single-crystal gallium nitride (GaN) substrates have been a research hot-spot. In this work, the synergistic effect of abrasive friction and glycine (Gly) on improving the chemical mechanical polishing (CMP) performance of single-crystal GaN substrate is proposed and studied systematically. The results indicated that the polishing solutions with Gly have a 2.3-fold improvement in material removal rate (MRR) as well as scratch-free surface than that without Gly. The maximum MRR of the single-crystal GaN substrate is 129.4 nm/h with surface roughness (Ra) of 0.64 nm attained by using the polishing solutions containing only 3 wt% potassium persulfate (K2S2O8). In contrast, when Gly is added as a reaction reagent, which can be activated by abrasive friction, the maximum MRR is increased to 304.2 nm/h with Ra of 0.42 nm. Meanwhile, the epitaxial evaluation indicates that two-dimensional (2D) MoS2 grown on processed single-crystal GaN substrate has superior crystalline quality and optical properties. Finally, the polishing mechanism of the single-crystal GaN substrate using the mixed solutions of K2S2O8 and Gly is discussed. The proposed CMP method has potential applications in the semiconductor and microelectronics industries.

Magnetic proximity interaction provides a promising route to manipulate the spin and valley degrees of freedom in van der Waals heterostructures. Here, we report a control of valley pseudospin in the WS2/MoSe2 heterostructure by utilizing the magnetic proximity effect of few-layered CrBr3 and, for the first time, observe a substantial difference in valley polarization of intra/interlayer excitons under different circularly polarized laser excitations, referred to as chirality-dependent valley polarization. Theoretical and experimental results reveal that the spin-selective charge transfer between MoSe2 and CrBr3, as well as between MoSe2 and WS2, is mostly responsible for the chiral feature of valley polarization in comparison with the proximity exchange field. This means that a long-distance manipulation of exciton behaviors in multilayer heterostructures can be achieved through spin-selective charge transfer. This work marks a significant advancement in the control of spin and valley pseudospin in multilayer structures.

Proximate-induced magnetic interactions present a promising strategy for precise manipulation of valley degrees of freedom. Taking advantage of the splendid valleytronic platform of transition metal dichalcogenides, magnetic two-dimensional VSe2 with different phases are introduced to intervene in the spin of electrons and modulate their valleytronic properties. When constructing the heterostructures, 1T-VSe2/WX2 (X = S and Se) showcases significant improvement in the valley polarizations at room temperature, while 2H-VSe2/WX2 exhibits superior performance at low temperatures and demonstrates heightened sensitivity to the external magnetic field. Simultaneously, considerable valley splitting with a large g(eff) factor up to -29.0 is observed in 2H-VSe2/WS2, while it is negligible in 1T-VSe2/WX2. First-principles calculations reveal a phase-dependent magnetic proximity mechanism on the valleytronic modulations, which is dominated by interfacial charge transfer in 1T-VSe2/WX2 and the proximity exchange field in 2H-VSe2/WX2 heterostructures. The effective control over valley degrees of freedom will bridge the valleytronic physics and devices, rendering enormous potential in the field of valley quantum applications.

Two-dimensional molybdenum disulfide (2D MoS2), with atomic-level thickness, whose crystal crystallinity and size are easily influenced by the surface morphology of the substrate during growth. This work systematically investigates the impact of chemical mechanical polishing (CMP) sapphire substrate on chemical vapor deposition (CVD) growth of 2D MoS2. A green and highly efficient CMP method for the sapphire substrate is first proposed, whose maximum material removal rate (MRR) of 4.27 µm/h with surface roughness (Ra) of 0.10 nm (AFM, scanning area of 5 × 5 μm2) can be attained. The size and thickness statistics of 2D MoS2 domains grown on different substrates indicate that the CMP sapphire substrate in this work can promote the size and monolayer uniformity of 2D MoS2 during CVD growth. Meanwhile, Raman and photoluminescence (PL) spectra of monolayer MoS2 grown on different substrates also indicates the monolayer MoS2 grown on the CMP sapphire substrate in this work has superior crystalline quality and optical properties. The above findings have provided new insights into the mechanisms underlying 2D MoS2 growth on surfaces in various states and are expected to accelerate the development of large size large-size and high-quality growth of two-dimensional material for further device applications.

Over the past decade, significant advancements have been made in phase engineering of two-dimensional transition metal dichalcogenides (TMDCs), thereby allowing controlled synthesis of various phases of TMDCs and facile conversion between them. Recently, there has been emerging interest in TMDC coexisting phases, which contain multiple phases within one nanostructured TMDC. By taking advantage of the merits from the component phases, the coexisting phases offer enhanced performance in many aspects compared with single-phase TMDCs. Herein, this review article thoroughly expounds the latest progress and ongoing efforts on the syntheses, properties, and applications of TMDC coexisting phases. The introduction section overviews the main phases of TMDCs (2H, 3R, 1T, 1T ', 1T(d)), along with the advantages of phase coexistence. The subsequent section focuses on the synthesis methods for coexisting phases of TMDCs, with particular attention to local patterning and random formations. Furthermore, on the basis of the versatile properties of TMDC coexisting phases, their applications in magnetism, valleytronics, field-effect transistors, memristors, and catalysis are discussed. Lastly, a perspective is presented on the future development, challenges, and potential opportunities of TMDC coexisting phases. This review aims to provide insights into the phase engineering of 2D materials for both scientific and engineering communities and contribute to further advancements in this emerging field.

The bilayer (BL) transition metal dichalcogenides (TMDs), with their elevated carrier mobility and narrowed bandgap, are advantageous for future electronic applications in comparison with their monolayer (ML) counterparts. Here, we introduce a facile and efficient approach for the chemical vapor deposition synthesis of BL WS2. The method involves an acetic acid sonication treatment to modify the substrate surface morphology and the surface energy, which regulates the nucleation processes and shapes the growth mode of WS2 crystals. Further modifications to the growth conditions yield high-quality ML and BL WS2 films. A comparative study confirms the superior valley polarization and higher carrier mobility of BL WS2 compared with its ML counterpart. Additionally, a minor twist angle existed between the upper and lower layers, featuring a Moiré superlattice. This work reveals the role of surface morphology and surface energy in the growth of TMDs. Simultaneously, it offers insights into the controlled preparation of vertically stacked homo- and heterojunctions.

High-efficiency deep-ultraviolet (DUV) micro light-emitting diodes (LEDs) are explored for inspiring development in numerous fields, such as non-line-of-sight solar-blind communication, optical pumping, and maskless lithography. In this study, we performed FDTD and SimuLED calculations to investigate the optimized DUV micro-LED structure geometry for high light extraction efficiency (LEE) by designing different mesa structures, including square, hexagonal, and circular geometries of micro-LEDs emitted at a wavelength of 275 nm. The results showed that a circular mesa of 5 mu m diameter achieved a LEE of 27% from the bottom and sidewall emissions of as-prepared DUV micro-LED. And both the near- and far-field transverse magnetic polarized light intensities were enhanced by a factor of 1.5 over the square and hexagonal mesas. Meanwhile, the transverse electric (TE) polarized light of the circular mesa structure was enhanced and concentrated along the normal direction. Moreover, the internal quantum efficiency (IQE) of circular mesas with varied sizes was comprehensively investigated in the interactions of the thermal and electric fields. An AlGaN-based DUV micro-LED with a diameter of 5 mu m was found to obtain the highest IQE owing to a high current-density distribution and its self-heating properties, thereby achieving a sufficiently high external quantum efficiency of 26.75%. This study provides a comprehensive technical report, including electrical, thermal, and optical analyses, and a new perspective for developing high-efficiency, high-performance DUV micro-LEDs in practical applications.

With the rapid development of the third-generation semiconductors, environmentally friendly tribochemical mechanical polishing (TCMP) is in urgent need and has been a research hot-spot. In this work, the mechanism of glycine (Gly) and H2O action in TCMP of single-crystal gallium nitride (SC-GaN) substrate is systematically studied. The experimental results indicate that the TCMP of SC-GaN substrate with 0.75 wt% Gly exhibits a higher surface quality and a 3-fold improvement in material removal rate than that with H2O. Based on first-principle calculations, the geometric configurations and interfacial interactions of the Gly/SC-GaN and H2O/SC-GaN heterostrutures are further explored. Charge transfer analysis shows that SC-GaN with lattice distortion of 0.4 & Aring; transfers more electrons into Gly (0.202 e) than into H2O (0.128 e), which suggests the reaction between SC-GaN and Gly is more intense under friction by abrasives. The research of differential charge density and geometric properties (bond angles etc.) demonstrates that the -COOH functional group (Gly) has a higher reactivity than the -OH functional group (H2O). Based on the above findings, a microscopic material removal model for the TCMP of SC-GaN substrate with Gly is established. These results have potential applications in the semiconductor and microelectronics industries.

In this work, the strain engineering on the electronic and spintronic properties of PtS2/MoTe2 heterostructure is investigated by first-principle calculations. Based on the energy minimum principle, the most stable configuration of the PtS2/MoTe2 heterostructure is recognized. The mechanisms for the evolution of the band structures under different strains are analyzed by the atomic orbital projected band structures. Furthermore, a Rashba type spin texture of PtS2/MoTe2 heterostructure is predicted, with a formation mechanism revealed through atomic orbital projected spin textures. The strain tunable electronic and spintronic properties of PtS2/MoTe2 heterostructure hold great promise in applications of spintronics and nanoelectronics.

Phytoplankton face numerous pressures resulting from chemical and physical stressors, primarily induced by human activities. This study focuses on investigating the interactive effects of widely used antifouling agent Irgarol 1051 and UV radiation on the photo-physiology of marine diatoms from diverse latitudes, within the context of global warming. Our findings clearly shown that both Irgarol and UV radiation have a significant inhibitory impact on the photochemical performance of the three diatoms examined, with Irgarol treatment exhibiting more pronounced effects. In the case of the two temperate zone diatoms, we observed a decrease in the inhibition induced by Irgarol 1051 and UVR as the temperature increased up to 25°C. Similarly, for the subarctic species, an increase in temperature resulted in a reduction in the inhibition caused by Irgarol and UVR. These results suggest that elevated temperatures can mitigate the short-term inhibitory effects of both Irgarol and UVR on diatoms. Furthermore, our data indicate that increased temperature could significantly interact with UVR or Irgarol for temperate diatoms, while this was not the case for cold water diatoms, indicating temperate and subarctic diatoms may respond differentially under global warming.

With the rapid development of novel optoelectronic devices, an environmentally friendly and highly efficient polishing technology for SC-sapphire substrates is imminent. In this work, the micro-mechanism of Gly action in TCMP of SC-sapphire substrate is systematically studied by TCMP experiments and first-principles calculations. The results of TCMP experiments confirm that the maximum MRR of 5.37 mu m/h with Ra of 0.42 nm can be attained at optimal concentration of Gly, without any acid or alkali corrosive solution. The first-principles calculations of the Gly/SC-sapphire heterostructure further reveal the reaction behavior of the -COOH functional group with and without lattice distortion. The results of both TCMP experiments and VASP simulations demonstrate that the incorporation of Gly can facilitate the friction-induced Gly/SC-sapphire reaction, which significantly enhances the processing surface quality and the processing efficiency of SC-sapphire substrates. Finally, based on the above research, a microscopic material removal model for the Gly-based SC-sapphire substrate TCMP is constructed. The above findings are of great significance in promoting the development of green ultra-precision polishing technology for semiconductor substrates.