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Research Article Controllable valley magnetic response in phase-transformed tungsten diselenide a,b a a a, a, a a Haiyang Liu, Zongnan Zhang, Yingqiu Li, Yaping Wu, * Zhiming Wu , * Xu Li , Chunmiao Zhang, a a Feiya Xu , and Junyong Kang Xiamen University, Engineering Research Centre for Micro-Nano Optoelectronic Materials and Devices at Education Ministry, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Department of Physics, Xiamen, China Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore Abstract. Achieving valley pseudospin with large polarization is crucial in the implementation of quantum information applications. Transition metal dichalcogenides (TMDC) with different phase structures provide an ideal platform for valley modulation. The valley splitting has been achieved in hybrid phase WSe , while its valley polarization remains unstudied. Magnetic field controllable valley polarization is explored in WSe with coexistence of H and T phases by an all-optical route. A record high valley polarization of 58.3% is acquired with a 19.9% T phase concentration under a 4-T magnetic field and nonresonant excitation. The enhanced valley polarization is dependent on the phase component and shows various increasing slopes, owing to the synergy between the T phase WSe and the magnetic field. The magnetic field controlled local magnetic momentums are revealed as the mechanism for the large valley polarization in H∕T-WSe . This speculation is also verified by theoretical simulations of the nonequilibrium spin density. These results display a considerable valley magnetic response in phase-engineered TMDC and provide a large-scale scheme for valley polarization applications. Keywords: phase engineering; transition metal dichalcogenides; valley polarization; magnetic field; valley magnetic response. Received Jan. 25, 2023; accepted for publication Feb. 6, 2023; published online Mar. 2, 2023. © The Authors. Published by SPIE and CLP under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.APN.2.2.026007] 10,11 heterojunction construction. Alternatively, applying a mag- 1 Introduction netic field to induce nonequilibrium spin states through the Inversion symmetry breaking, strong spin–orbit coupling, and Zeeman field is considered an essential method for regulating time inversion symmetry give rise to two nonequivalent valleys the valley dynamics. However, due to the semiconductor prop- (K and K ) with antiparallel spins in monolayer transition metal erty of H phase TMDC materials, a high magnetic field is gen- 1–3 dichalcogenides (TMDCs). Regulating the valley dynamics has 12 erally necessary to achieve a larger valley polarization. Further, 4,5 attracted considerable attention in recent years. Polarization- combining with the spin injection through a magnetic hetero- resolved photoluminescence (PL) used to optically encode and junction or ferromagnetic electrode, the magnitude of a required unbalance the spin population in the two valleys can express magnetic field can be reduced by taking advantage of the in- the carried binary information by the intensity of emitted lights. 13–15 jected nonequilibrium spin carriers. Nevertheless, the com- Realization high valley contrast is the key to establishing a prom- plicated growth process and specially designed structures result ising platform for both optoelectronic and spintronic applications. in the lattice mismatch and poor integrability of devices. The strategies for enhancing the valley contrast mainly focus Meanwhile, the clean interface and conductivity matching are on suppressing the intervalley scattering by plasmonic meta- indispensable for efficient spin injection, which are difficult 6,7 8,9 surface, defects and strain engineering, or breaking the in- to control precisely in the magnetic heterojunction. To introduce version symmetry by electrical modulation, twist staking, and the spin electrons, we came up with idea of bringing in the T phase into origin H phase monolayer of TMDC. Instead of ap- plying additional conditions on TMDC, the phase engineering *Address all correspondence to Yaping Wu, ypwu@xmu.edu.cn; Zhiming Wu, could modify the intrinsic structure of materials to enhance the zmwu@xmu.edu.cn Advanced Photonics Nexus 026007-1 Mar∕Apr 2023 Vol. 2(2) Liu et al.: Controllable valley magnetic response in phase-transformed tungsten diselenide valley magnetic response. Compared with the H phase TMDC, as the mechanism for the enhanced valley magnetic response 16–20 the T phase with partial filling of the nonbonding d bands and thus the large valley polarization in hybrid H∕T-WSe . can be modulated sensitively by the magnetic field and induce net spin in the hybrid H/T system. The synergy between the 2 Results and Discussion internal magnetic component and the external magnetic field will considerably increase the effective Zeeman field, promote 2.1 Synthesis of Hybrid Phase Monolayer H/T-WSe the exchange interaction, and enhance the valley polarization of 15,21,22 Monolayer WSe with an H/T hybrid phase is prepared through TMDC. As a result, the valley splitting has been verified in hybrid-phase TMDC, demonstrating its potential application a CVD synthesis followed by a moderate Ar plasma treatment in valleytronics. However, there is still a lack of detailed valley (detailed in Sec. 4). As the optical morphology shows in magnetic response study on the valley polarization of hybrid- Fig. 1(a), WSe film after Ar plasma treatment exhibits a uni- phase TMDC. In addition, H/T hybrid phase TMDC can be form thickness contrast and a large scale of more than 500 μm easily prepared by the chemical vapor deposition (CVD) in lateral size. The atomic force microscopy (AFM) characteri- method followed by a controllable plasma treatment or alkali zation is performed to confirm its monolayer thickness, as pro- 24–28 metal intercalation, which will be a feasible, convenient, vided in Fig. S1 in the Supplementary Material. Figure 1(b) and scalable method for regulation of the valley magnetic re- shows the high-resolution transmission electron microscopy sponse in TMDC materials. (HRTEM) image of the film. The lattices clearly display two In this work, large-scale H∕T-WSe monolayers with con- different configurations of hexagon honeycomb and zigzag trollable components are synthesized. The structure with the chain, corresponding to the H and T phase WSe , respec- 29,30 higher T phase concentration is demonstrated to possess larger tively. Selected area electron diffraction (SAED), shown valley polarization and higher sensitivity to the external mag- in Fig. 1(c), has two coexisting hexagonal patterns, which also netic field. A record high degree of valley polarization is verify the contribution from the H and T phases, respectively. achieved in monolayer H∕T-WSe with 19.9% T phase concen- Moreover, the phase component can be well controlled by trations. The density functional theory (DFT) simulations indi- adjusting the Ar plasma power and treatment time. As is an- cate the higher electron concentration and nonequilibrium spin alyzed by X-ray photoelectron spectroscopy (XPS) in Fig. 1(d), density as incorporating the T phase. The local magnetic mo- two H∕T-WSe monolayers with different T phase components mentums arranged by external magnetic field are considered are verified. Among the four characteristic peaks of W , the 4f Fig. 1 (a) Optical topography of the CVD-grown large-scale WSe monolayer on SiO ∕Si 2 2 surface, where the tweezer trace shows the distinction between WSe film and the substrate. (b), (c) HRTEM image and SAED pattern of monolayer H∕T-WSe . (d) XPS of monolayer H∕T-WSe . The blue and purple shadows correspond to the components of H and T phases, respectively. (e) I–V curves of monolayer H-WSe and H∕T-WSe with the T-phase components 2 2 of 12.2% and 19.9%. (f) Atomic structure of monolayer H∕T-WSe , and the differential charge densities of top Se, W, and bottom Se atomic layers. The scale bar from blue to red denotes the change from depletion to accumulation. Advanced Photonics Nexus 026007-2 Mar∕Apr 2023 Vol. 2(2) Liu et al.: Controllable valley magnetic response in phase-transformed tungsten diselenide blue set located at 34.5 and 32.4 eV corresponds to the H phase peak or the change of peak position is observed before and after WSe , and the purple set centered at 33.8 and 31.7 eV corre- the phase transition, which indicates that the defect number pro- sponds to the T phase. The gray area presents the traces of duced by the plasma treatment should be small and its influence oxidized tungsten. By fitting the area of XPS peaks, the T phase on the valley polarization should be negligible. The degree of components are estimated to be 12.2% and 19.9% T, respec- valley polarization is quantitatively evaluated according to tively. So far, the structure of H∕T-WSe is confirmed by in- the expression ρ ¼ðI − I Þ∕ðI þ I Þ for left-handed LL LR LL LR tuitive transmission electron microscopy (TEM) observation circularly polarized excitation (σ )or ρ ¼ðI − I Þ∕ RR RL and quantitative XPS analysis. ðI þ I Þ for right-handed circularly polarized excitation RR RL Considering that higher electron concentration will be ben- (σ ), where I (I ) and I (I ) denote the intensities of LL RR LR RL eficial to the valley polarization, the current–voltage (I–V) prop- circularly polarized emissions with a co- and cross-polarized erty is further studied to estimate the conductivity of the configurations, respectively. The intrinsic valley polarization samples. Figure 1(e) exhibits a larger slope of the I–V curve is calculated as 9.0% [Figs. S2(a) and S2(b) in the Supple- for 19.9% of the T-phase sample, indicating that the electron mentary Material] for H∕T-WSe -12.2% and further promotes concentration is increased with the increasing T-phase compo- to 12% [Figs. S2(c) and S2(d) in the Supplementary Material] nent. This can be attributed to the metallicity of the introduced when the T-phase component increases to 19.9%. It is also T phase. Local interaction between the T- and H-phase W atoms noteworthy that the valley polarization is controllable under (W and W ) is investigated from the calculated layer- T H the external magnetic field. Compared with the co-polarized dependent 2D charge distribution, as shown in Fig. 1(f).It signal, the suppression of the cross-polarized peak under the can be found that the top three Se atoms of the T phase possess magnetic field is a signature of modulation on the optical valley 3,32–34 fewer electrons by about 0.03 e than other Se atoms, and the six polarization in H∕T-WSe . Taking the H∕T-WSe -19.9% 2 2 nearest-neighbor W atoms around the W atoms lose fewer H T as an instance, the valley polarization varies from 45.4% to electrons by about 0.07 e than other W atoms. The charge– 58.3% when the magnetic field increases from 1 to 4 T, and transfer interactions predict the ability to control the properties − the maximum value of 58.3% is obtained for the σ excitation of H-WSe through the introduced T phase. under a magnetic field of 4 T [Figs. 2(a)–2(d)]. A similar en- hanced trend is also found for the magnetic field increased from 2.2 Characterization of Valley Polarization −1 to −4T [Figs. 2(e)–2(h)]. It should be noted that the ob- tained valley polarization in H∕T-WSe is much larger than that Valley polarization enhancement in H∕T-WSe with different of pure H-WSe , and the maximum value is record-high under T-phase concentrations (12.2% and 19.9%) is verified through 13,36,37 the nonresonant excitation so far. the circularly polarized PL spectra at 10 K, as shown in Fig. 2. The magnetic field-dependent valley polarizations with σ Each spectrum exhibits a single peak around 1.72 eV, consistent excitation are compared and depicted in Figs. 3(a) and 3(b) with the energy of the neutral exciton (X ). No additional defect Fig. 2 Circularly polarized PL spectra of H∕T-WSe -19.9% under (a)–(d) positive magnetic fields from 1 to 4 T and (e)–(h) negative magnetic field from −1to −4 T. The blue and purple lines indicate co- and cross-polarized configurations, respectively. Advanced Photonics Nexus 026007-3 Mar∕Apr 2023 Vol. 2(2) Liu et al.: Controllable valley magnetic response in phase-transformed tungsten diselenide Fig. 3 Magnetic-dependent polarization of (a) H∕T-WSe -12.2% and (b) H∕T-WSe -19.9% under 2 2 − − þ σ excitation with σ and σ detection. The red dots indicate the measurement data. The dark blue, light blue, and pink lines show slopes from 0 to 1T, 1to 2 T, and 2to 4 T, respectively. Spin density isosurface plots of (c) H-WSe and (d) H∕T-WSe . The W and Se atoms are denoted 2 2 by the blue and yellow balls, respectively. The isosurface in pink represents the majority spin den- sity. Total spin DOSs of monolayers (e) H-WSe and (f) H∕T-WSe , where the pink and blue lines 2 2 denote the majority and minority spin DOS. for different T-phase concentrations. The results at 0 T are Material. In the framework of crystal field theory, H-WSe 11.3% [Fig. 3(a)] and 12.0% for H∕T-WSe -12.2% and has a trigonal prismatic coordination, and the W-4d orbital H∕T-WSe -19.9% [Fig. 3(b)], respectively, and the evolution splits into three energy levels, as shown in Fig. S5 in the curves exhibit as a “V” pattern with different slopes from −4to Supplementary Material. T-WSe is an octahedral coordination þ4T for both the samples. Specifically, in H∕T-WSe -12.2%, and the W-4d orbital splits into two energy levels, i.e., double- 2 2 2 the valley polarization increases sharply from 0 to 1 T (−1T) degenerate e ðd ; d Þ and triple-degenerate t 2g x x −y 2g with a slope of 0.30 (0.28). As the magnetic field further ðd ; d ; d Þ. The t is partly occupied in parallel by the xy xz yz 2g increases, the increasing trend of valley polarization becomes two 4d electrons to reduce the coulomb energy between the 4d electrons, producing a 2-μ net magnetic moment for the W smooth, corresponding to the slopes of 0.08 from 1 to B atom. Therefore, the nonequilibrium spin distribution and 2T, and 0.02 from 2 to 4T. Compared with the former the induced magnetic moment in the system may be aligned case, H∕T-WSe -19.9% is more sensitive to the magnetic field, by the external magnetic field, which will facilitate the gener- exhibiting a larger slope of 0.46 from 0 to 1T, and gradually ation and modulation of the valley polarization. decreased slopes of 0.06 from 1 to 2T and 0.02 from 2 to 4T. A similar phenomenon is also observed for the σ exci- tation, as shown in Fig. S3 in the Supplementary Material. 2.3 Qualitative and Quantitative Analysis of Valley To gain a comprehensive understanding of the role of the Polarization in H/T-WSe magnetic field, the first-principle simulations are performed Based on the above experimental and simulation results, the to compare the spatial distribution of the spin density for mono- enhanced valley polarizations in H∕T-WSe are qualitatively an- layer H-WSe and H∕T-WSe . As shown in Figs. 3(c) and 3(d), 2 2 alyzed in terms of nonequilibrium spin distribution in H∕T-WSe the net spin in H-WSe is zero, whereas pronounced spin den- and quantitatively calculated from the increased electron concen- sities are induced by the W atom in H∕T-WSe and distributed T 2 tration in H∕T-WSe ,asdepictedinFigs. 4(a)–4(e).The around the six nearest W atoms. Figures 3(e) and 3(f) show H 38 Hamiltonian of the valley exciton can be expressed as the total spin density-of-states (DOSs) for monolayer WSe be- fore and after the phase transition, respectively. For the H-WSe , 2 2 ℏ k the DOS exhibits a symmetric distribution for the spin-up H ¼ ℏw þ þ V ðkÞþ τ V ðkÞþ τ V ðkÞ 0 þ inter − inter 2M and spin-down states, indicating a nonmagnetic ground state 0 [Fig. 3(e)]. For H∕T-WSe , the DOSs split into asymmetric 2 σ ˆ − 1 þ ðs ˆ þ ταÞB: spin-up and spin-down channels, echoing a nonequilibrium distribution in spin density [Fig. 3(f)]. The main contribution of the asymmetric DOSs in H∕T-WSe is from the 4d state of W The first term, ℏw ∼ 1.72 eV, represents the exciton energy 2 T 0 rather than W , as shown in Fig. S4 in the Supplementary (k ¼ 0,where k is the distance from K to Γ point in the first Advanced Photonics Nexus 026007-4 Mar∕Apr 2023 Vol. 2(2) Liu et al.: Controllable valley magnetic response in phase-transformed tungsten diselenide Fig. 4 Schematic diagram of magnetic-field-modulated valley dynamic process of monolayer H-WSe and H∕T-WSe . (a) SOC-induced valence band splitting in H-WSe . (b) SOC induced 2 2 2 band splitting in H∕T-WSe with the electron concentration increases due to the introduction of T phase in H-WSe . (c) Magnetic-field-induced exciton dispersion in conduction band and valley splitting in valence band of H∕T-WSe . (d) Cartoons depicting valley polarization in H∕T-WSe 2 2 under the (d) positive and (e) negative magnetic fields, respectively. The thick arrows with single color (γ ) denote the asymmetric valley-conserving and the thin arrows (γ ) with color gradient 1 2 þ − denote the valley-flipping exciton formation processes under σ and σ excitation. Brillouin zone). M in the second term is the exciton mass, and magnetic field. Under a perpendicular magnetic field, the σ ˆ −1 0 z the third term V ðkÞ is the pseudospin-independent term. The induced Zeeman energy ðs ˆ þ ταÞB results in the two- intervalley electron–hole exchange leads to the fourth term branch exciton dispersion by opening up a finite gap at −2iθ V ðkÞ¼ VðkÞe , where the center-of-mass wave vector is k ¼ 0, as shown in both the conduction and valence bands in inter represented by k ≡ ðk ;k Þ¼ ðk cos θ;k sin θÞ and the exciton Fig. 4(b). Simultaneously, the T-phase component with certain x y valley pseudospin is described by the Pauli matrix τ. The last magnetic momentums in WSe acts as local magnetic fields. term is the crucial exchange term describing the additional If these local magnetic momentums can be arranged in a unified Zeeman energy induced by the phase transition. direction, a valley splitting of ΔE will be acquired [Fig. 4(c)]. ex As is well known, the spin–orbital coupling (SOC) interac- Taking the 19.9% T-phase concentration as an example, the tion will induce the splitting in the valence band, producing the maximum ΔE is calculated about 38.5 meV, as shown in ex spin-valley locking effect [Fig. 4(a)] and circular polarization Fig. S6 in the Supplementary Material. The induced intrinsic in the PL helicities. WSe with higher electron concentration nonequilibrium spin distribution is much larger than the latest will involve more electrons in the excitons process, transferring reported spin injection from Fe GeTe or any other interme- 3 2 oscillator strength from the exciton to the attractive Fermi po- dium manipulating the valley polarization. Therefore, although laron, resulting in the polarization enhancement. Therefore, the absolute value of valley-conserving rate γ and valley- the valley polarization can be quantitatively increased with flipping rate γ will switch with the change of magnetic field þ − − þ the increasing T-phase concentration under the σ and σ ex- direction, resulting in larger valley polarization for σ (σ ) ex- þ − citations, as observed in the above two different components of citation than for σ (σ ) excitation under positive (negative) monolayer H∕T-WSe . Without the magnetic field, the nonequi- magnetic field [Figs. 4(d) and 4(e)], the effect of magnetic field librium spin in H∕T-WSe generates local magnetic moments on the valley excitons dispersion is limited. Consequently, the with random directions. The overall statistical average should valley polarization increases with both the increased positive or not show a long-range magnetism that can be equivalent to a negative magnetic fields, as shown in Figs. 3(a) and 3(b). Advanced Photonics Nexus 026007-5 Mar∕Apr 2023 Vol. 2(2) Liu et al.: Controllable valley magnetic response in phase-transformed tungsten diselenide According to above analysis, it can be concluded that there WO (Alfa Aesar, 99.9%) film on an SiO ∕Si chip and the 3 2 are three possible physical processes dominating the polariza- Se powder (Aladdin, 99.99%) serve as the precursors of W tion: (i) the increased electron concentration. Without the mag- and Se sources, respectively. H∕T-WSe is obtained based on netic field, the valley polarization is mainly determined by the monolayer H-WSe through an Ar plasma treatment. The ra- dio-frequency power and flow rate of high pure Ar gas are set as optical valley polarization and enhanced by the increased elec- 1 W and 0.5 sccm, respectively, under a 100-Pa background tron concentration, i.e., the T-phase component. (ii) The synergy pressure at room temperature. A cold, moderate Ar plasma between the T phase and the external magnetic field. With the atmosphere is formed on the surface of WSe , enabling partial magnetic field, the T-phase-induced nonequilibrium spins are 18,40 − þ H to T phase transition. Since the formation energies of W well aligned, resulting in an obvious σ (σ ) response with and Se vacancy defects are higher than the energy required for the spin-up (spin-down) electrons. This explains the sharply in- 40–43 the H-to-T phase transition, the plasma power and time can creased slopes of valley polarization from 0 to 1T, as the dark be well controlled during the plasma treatment process to pro- blue lines shown in Fig. 3(a). (iii) The magnetic field induced mote the phase transition rather than forming defects. Zeeman effect. The initial magnetic field within 1T could al- ready align most of the magnetic momentums of the T phase. As the magnetic field increases further, it will align the rest small 4.2 First-Principles Calculations part of nonequilibrium spins of the T phase and increases the The differential charge densities of H-WSe and H∕T-WSe are 2 2 Zeeman field simultaneously, resulting in a moderate increased calculated using the DFT. The 4 × 4 × 1 supercells of H-WSe slope of valley polarizations from 1 to 2T [light blue lines and H∕T-WSe monolayers are constructed by considering the in Fig. 3(b)]. Although in the magnetic field range from 2 to measured phase components. The T phase in H∕T-WSe is in- 4T, only the magnetic-field-induced Zeeman effect domi- troduced by wrenching the Se-W bonds locally by 60 deg nates the enhancement of valley polarizations, corresponding around the W atom. To avoid the artificial interaction between to even smaller slopes, as the pink lines depict in Figs. 3(a) the periodic slabs, an optimized vacuum layer of 20 Å is set. A and 3(b). Thus the enhanced valley polarization is achieved Monkhorst–Pack grid of the k points is sampled with a in the lateral H∕T-WSe . Besides the lateral structure, the valley 19 × 19 × 1 mesh in the Brillouin zone, and the plane-wave polarization may also realize a vertical H/T heterostructure. cutoff energy is set at 500 eV. The residual forces converge Compared with the strong bonding interaction, the van der −6 to <0.01 eV∕Å and the energy <1 × 10 eV for structural op- Waals interaction in the vertical heterostructure is much weaker, timization. and the induced local magnetic moment may be smaller. However, the contact area of H and T phases in the vertical het- 4.3 Characterizations erostructure can be larger than that of the lateral one, and there may be new properties and interactions. Therefore, the explora- The morphology and structural characterizations are performed tion of valley polarization in vertical H/T phase heterostructure by XPS (Quantum 2000), AFM (SPA400-Nanonavi), and TEM is ongoing. (JEM-2100, 200 kV) techniques. The magnetic-field-dependent circularly polarized PL spectra are obtained at 10 K with a 3 Conclusion 633-nm laser, and the magnetic fields are applied perpendicu- larly to the plane of the samples. The optical path diagram is In summary, large-scale monolayer H∕T-WSe with control- shown in Fig. S7 in the Supplementary Material. For the polari- lable phase concentrations are synthesized through the CVD zation resolved PL system, the left- and right-handed circularly method followed by an Ar plasma treatment. The polarized polarized excitation lights are produced through a linear polar- PL spectra suggest a component-dependent valley polarization, izer and a quarter-wave plate (λ∕4) in the excitation path. The which can be further modulated by the external magnetic field. polarization of emission lights is analyzed by the quarter-wave Owing to the enhanced valley magnetic response, a record-high plate and another linear polarizer in the detection path. valley polarization of 58.3% is achieved successfully in mono- layer H∕T-WSe -19.9% under a magnetic field of 4 T and non- resonant excitation. DFT calculations indicate the high electron Acknowledgments concentration and nonequilibrium spin density distribution in This work was supported by the National Science Fund for H∕T-WSe . Accordingly, three possible physical mechanisms, Excellent Young Scholars (Grant No. 62022068), the National including the increased electron concentration, the synergy be- Natural Science Foundation of China (Grant Nos. 61874092, tween the T phase and the external magnetic field, and the mag- 61974123, 61804129, and 62274139), and the Science and netic-field-induced Zeeman effect are analyzed qualitatively and Technology Project of Fujian Province of China (Grant Nos. quantitatively to understand the enhanced valley magnetic re- 2018I0017 and 2019H0002). H. Y. L., Y. P. W., and Z. M. W. sponse and thus the large valley polarization. All these results proposed this project. H. Y. L. implemented the material growth, fully explore the role of T phase in valley polarization under the experimental measurement, theoretical calculation, and analysis effect of external magnetic field, and provide a promising per- data. Z. N. Z. and Y. Q. L. participated in the analysis and dis- spective for a large-scale, all-optics-controlled valley dynamic cussion of calculation results. Y. P. W. and Z. M. W. participated manipulation. in the supervision, analysis of experimental results and theoreti- cal analysis, discussions, and article optimization. X. L. and 4 Methods J. Y. K participated in the supervision and discussion. C. M. Z. and F. Y. X took part in the experimental optimization 4.1 Preparation of Monolayer H-WSe and H/T-WSe 2 2 and testing. All authors participated in project implementation, CVD technology compatible with large-scale growth is used to discussion, and writing. The authors declare no conflicts of prepare monolayer H-WSe on sapphire substrates. 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Park et al., “Synthesis of 1T WSe on an oxygen-containing surface structure, spin transport, and solar cells. substrate using a single precursor,” ACS Nano 16, 11059–11065 (2022). Biographies of the authors are not available. Advanced Photonics Nexus 026007-7 Mar∕Apr 2023 Vol. 2(2)
Advanced Photonics Nexus – SPIE
Published: Mar 1, 2023
Keywords: phase engineering; transition metal dichalcogenides; valley polarization; magnetic field; valley magnetic response
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