Advanced Photonics Nexus
·
2023
·
IF 0
Haiyang Liu,Zongnan Zhang,Yingqiu Li,Yaping Wu,Zhiming Wu,Xu Li,Chunmiao Zhang,Feiya Xu,Junyong Kang
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 WSe2, while its valley polarization remains unstudied. Magnetic field controllable valley polarization is explored in WSe2 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 WSe2 and the magnetic field. The magnetic field controlled local magnetic momentums are revealed as the mechanism for the large valley polarization in H / T-WSe2. 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.
研究领域:
凝聚态物理
·
材料科学
·
量子信息
·
光学调控
·
二维材料
✓ 已验证
DOI
Journal of Physical Chemistry C
·
2023
·
IF 3.7
Maomiao Xiang,Jun Fu,Chenxi Huang,Yue Xing,Jiefu Zhang,Hualing Zeng,Xiang Shao
Monolayer transition-metal dichalcogenides (TMDs) have registered attractive potential applications in optoelectronics, spintronics, and valleytronics. Here, we develop a simple chemical vapor deposition method to directly grow large-size monolayer WS2 on an atomically flat rutile TiO2(110) substrate. The variety of microscopic and spectroscopic characterizations reveals the highly single crystallinity of the as-grown WS2 and the atomically clean WS2/TiO2 interface. Such structural perfection renders a neutral excitonic photoluminescence of WS2 with extremely small spectral broadening of around 20 meV at cryogenic temperature. Moreover, the low concentration of defect leads to the suppressed intervalley scattering, while the efficient interfacial electron transfer reduces the Coulomb interaction between the valleys of the WS2, which thus enhance the valley polarization and coherence significantly so that it can reserve up to room temperature under ambient conditions. These results demonstrate that the substrate tuning corroborated by interface control can be a promising strategy to utilize the TMDs in practical valleytronics.
研究领域:
材料科学
·
凝聚态物理
·
光学
✓ 已验证
DOI
高影响因子
Laser & Photonics Reviews
·
2025
·
IF 10
Haiyang Liu,Mengyu Liu,Chunmiao Zhang,Feiya Xu,Xuanli Zheng,Xu Li,Zhiming Wu,Yaping Wu,Junyong Kang
Janus transition metal dichalcogenides host a unique structural asymmetry that enhances their potential for spintronics and valleytronics. Here, using a phase engineering strategy, a hybrid H/T-MoSeS monolayer is synthesized via in situ plasma substitution. Theoretical analysis predicts a valley splitting of 7.35 meV, which is experimentally realized, with a 2.7-fold enhancement in the g-factor compared to the H-MoSeS. The substantial valley splitting originates from the additional exchange interactions and spin imbalance introduced by the T-phase. The coupling with the T phase further results in electrically tunable valley polarization, which reveals a sharp increase within ±20 V, gradually saturates at higher voltages, and reaches a high ratio of up to 43.8% for trions at room temperature. Such an enhancement is accompanied by elongated exciton lifetimes due to the increased electron concentration and phase-modulated Janus polarization field. All these findings reveal the synergistic interplay between phase engineering and the polarization field in Janus structures, providing a development strategy for 2D spin-valley devices with designed phase components and structural symmetry.
研究领域:
凝聚态物理
·
材料科学
·
纳米科技
·
半导体物理
·
低维材料
·
自旋电子学
·
激子学
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 28
·18998-19003
·
IF 3.3
Guangcun Gao,Jintong Zhu,Songrui Wei,Yang Cao,Wei Huang,Zhongxin Liu,Jieqiong Wang,Yijun Shen
Monolayers of transition metal dichalcogenides (TMDCs) are atomically thin direct-bandgap semiconductors with potential applications in nanoelectronics, opto-electronics, and electrochemical sensing. Recent theoretical and experimental results have suggested that they are ideal systems for exploiting the valley degrees of freedom of Bloch electrons. Here, we report detailed studies of the opto-valleytronic properties of a chiral histidine molecule embedded in monolayer MoS2 single crystals grown via chemical vapor deposition. By irradiating MoS2 with circularly polarized light and measuring the resulting spatially resolved circularly polarized emission, we find the existence of a significantly increased circular polarization for D-histidine doped MoS2. The increased valley contrast is attributed to the selective enhancement of both the excitation and emission rates having one particular handedness of the circular polarization. These results provide a promising pathway to enhance the valley contrast for monolayer TMDCs at room temperature.
研究领域:
材料科学
·
纳米技术
·
光电学
·
半导体物理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Photonics
·
2024
·
IF 6.5
Qinxue Yin,Xiao Xing,Qiaoyan Hao,Zeyu Zhang,Chunwei Wang,Xingyu Yue,Ziwei Li,Wenjing Zhang,Yuxin Leng,Juan Du
Valleytronics, focusing on the charge carriers occupying valleys (local energy extrema) of the energy bands in semiconductors, demonstrates an additional degree of freedom besides the spin and charge. Usually, the inequivalent valley “states” in transition metal disulfides (TMDs) could be manipulated by external magnetic fields by controlling the valley-polarized carriers in spin-coupled valleys. Here, we found that the valley polarization of the photocurrent in ε-InSe could be intrinsically manipulated without the external field by the all-optical contactless method. The transient circular photogalvanic effect (CPGE)-induced photocurrent revealed by terahertz emission could be reversed only by selected pumping carriers from vertically split valence bands into different Rashba valleys. The switchable Rashba valley polarization, i.e., the optical orienting valley degree of freedom, could be fulfilled by the synergetic effects between the momentum-dependent Zeeman-like field due to the emergent nonzero Berry curvature and the Rashba splitting. Our results suggest that the spontaneous symmetry breaking could degenerate the given valley in ε-InSe and give a new roadmap for the manipulation of the valley degree of freedom intrinsically.
研究领域:
物理学
·
材料科学
·
光电学
·
半导体物理
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2025
·Vol. 17
·期 39
·23129-23138
·
IF 5.1
Mengya Li,Xinhui Yang,Chang Lu,Meili Long,Zhihui Chen,Haitao Chen,Xiaoming Yuan,Jun He
Anisotropic van der Waals (vdW) heterostructures are crucial for smart optoelectronic device development. Although transition metal dichalcogenides (TMDCs) like WS2 hold great potential for high-performance optoelectronic devices, their C3 rotational symmetry restricts polarization-sensitive applications. Crystal symmetry breaking of TMDCs by forming heterostructures is a powerful approach for achieving anisotropic optoelectronic properties. Considering the promising potential of the WS2/Te p–n heterostructure in broad photoresponse and enhanced nonlinearity, we successfully fabricated this heterostructure and investigated its anisotropic optical properties. The formation of the heterostructure induces interfacial symmetry breaking, and the interface shows twofold symmetry as confirmed by polarization-dependent second-harmonic generation (SHG) measurements. Moreover, the WS2/Te heterostructure exhibits enhanced SHG signals across the 850–1064 nm wavelength range. The interlayer anisotropic moiré potential induced by symmetry breaking leads to anisotropic Raman scattering and exciton emission with degrees of polarization (DOP) of 0.268 and 0.310. Furthermore, the heterostructure formation reduces intervalley scattering, enhancing valley polarization in WS2. In particular, the valley polarization degree of the trion in the heterostructure is 0.495 at 93 K. These results demonstrate the potential of the WS2/Te heterostructure for strong nonlinear optical responses and anisotropic optoelectronic properties, establishing a foundation for their broad application in next-generation photonic devices.
研究领域:
光电子学
·
纳米光子学
·
材料科学
·
非线性光学
·
凝聚态物理
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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