Article
Multidisciplinary Sciences
Nisarga Paul, Yang Zhang, Liang Fu
Summary: van der Waals (vdW) heterostructures formed by 2D magnets and semiconductors have provided a fertile ground for fundamental science and spintronics. First-principles calculations reveal a proximity exchange splitting of 14 meV (equivalent to an effective Zeeman field of 120 T) in the vdW magnet-semiconductor heterostructure MoS2/CrBr3, resulting in a 2D spin-polarized half-metal with carrier densities up to 1013 cm-2. The effect of large exchange coupling on the electronic band structure is explored in the presence of magnetic layers with chiral spin textures, such as skyrmions. A flat Chern band is found at a magic value of magnetization m-0.2 for Schrodinger and generally occurs for Dirac electrons. The magnetic proximity-induced anomalous Hall effect enables transport-based detection of chiral spin textures, and flat Chern bands provide an avenue for engineering various strongly correlated states.
Review
Chemistry, Multidisciplinary
Jing Liu, Pei Li, Hongsheng Zheng
Summary: Research on thermal transport in 2D materials, particularly focusing on high thermal conductivity in graphene, has been boosted. However, large discrepancies in thermal properties obtained from experiments require careful examination due to various factors. Further improvements in thermal characterization techniques are necessary for investigating energy transport in 2D materials.
Article
Nanoscience & Nanotechnology
Shao-Nan Chen, Xu-Shan Liu, Rong-Hui Luo, En-Ze Xu, Jian-Guo Tian, Zhi-Bo Liu
Summary: This study demonstrates a large enhancement in the thermal conductivity of a van der Waals heterostructure composed of few-layer hexagonal boron nitride (h-BN) and reduced graphene oxide (RGO). By controlling the reduction temperature of RGO and changing the thickness of h-BN, the thermal conductivity of RGO is increased by nearly 18 times.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Seungjun Lee, D. J. P. de Sousa, Young-Kyun Kwon, Fernando de Juan, Zhendong Chi, Felix Casanova, Tony Low
Summary: In this study, we investigate the twist-angle dependence of spin-orbit coupling proximity effects and charge-to-spin conversion in graphene/WSe2 heterostructures from first principles. We find that the charge-to-spin conversion strongly depends on the twist angle, with optimal standard Rashba-Edelstein and disorder-free spin Hall efficiencies achieved at approximately 30 degrees twisting. The symmetry breaking due to twisting also gives rise to an unconventional Rashba-Edelstein effect, where the electrically generated nonequilibrium spin densities possess spins collinear to the applied electric field. Our work provides a new perspective on the electrical generation of spins in van der Waals heterostructures.
Article
Chemistry, Multidisciplinary
Zhou Zhou, Renkang Song, Junbo Xu, Xiang Ni, Zijia Dang, Zhichen Zhao, Jiamin Quan, Siyu Dong, Weida Hu, Di Huang, Ke Chen, Zhanshan Wang, Xinbin Cheng, Markus B. Raschke, Andrea Alu, Tao Jiang
Summary: By studying single-layer and twisted bilayer alpha-MoO3/graphene heterostructures, we demonstrate active modulation of the optical response function through IR nanospectroscopic imaging. Our results reveal that graphene doping leads to an increase in the wavelength of phonon polaritons, while the changes in amplitude and dissipation rate differ from the initial expectations. These variations can be attributed to the intricate interplay of gate-dependent components of the phonon polariton complex momentum.
Article
Nanoscience & Nanotechnology
Zahra Razaghi, Seyed Ali Hosseini, Abdolreza Simchi
Summary: The effect of geometry and graphene contact on photosensitivity was studied in this work. WS2 nanosheets were prepared by chemical vapor deposition on Si/SiO2 wafers, and their morphology and structure were characterized by atomic force microscopy and Raman spectroscopy. Graphene nanosheets were prepared by the scotch-tape method. Devices composed of vdW heterostructures showed high photoresponsivity at 535 nm, but slightly inferior responses were detected in the visible wavelength range.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Chemistry, Multidisciplinary
Zhujun Huang, Edoardo Cuniberto, Suji Park, Kim Kisslinger, Qin Wu, Takashi Taniguchi, Kenji Watanabe, Kevin G. Yager, Davood Shahrjerdi
Summary: Heterostructures obtained from layered assembly of 2D materials have potential in new electronic device development, but achieving atomically clean interfaces remains a challenge. This study experimentally investigates the interface cleaning problem of polymer-contaminated heterostructures from an energy viewpoint and proposes a mechanism for fabricating large and clean heterostructures.
Article
Chemistry, Multidisciplinary
Zhao Liu, Antoine Hinaut, Stefan Peeters, Sebastian Scherb, Ernst Meyer, Maria Clelia Righi, Thilo Glatzel
Summary: The intercalation of graphene is an effective approach to modify the electronic properties of two-dimensional heterostructures. In this study, the growth and surface properties of ionic KBr layers altered by graphene were characterized. It was found that the introduction of graphene caused the disappearance of rippling of KBr islands on Ir(111) and a consistent change in both the work function and the frictional forces.
Article
Chemistry, Multidisciplinary
Lei Ye, Xuehui Xu, Siyu He, Yanping Liu, Yizheng Jin, Yang Michael Yang, Haiming Zhu
Summary: This study investigates the triplet sensitization of monolayer semiconductors and its potential for enhancing optoelectronic applications. The results show that triplet energy or charge can be transferred to the monolayer semiconductors, resulting in photoluminescence enhancement and long-lived charge separation. These findings demonstrate the great promise of molecular triplets in sensitizing 2D monolayer semiconductors and provide guidance for achieving enhanced optoelectronic applications.
Article
Chemistry, Physical
Liang Cai, Hengli Duan, Qinghua Liu, Chao Wang, Hao Tan, Wei Hu, Fengchun Hu, Zhihu Sun, Wensheng Yan
Summary: Realizing high-temperature ferromagnetism in two-dimensional (2D) semiconductor nanosheets is achieved by growing MoS2 Moire superlattice on a reduced graphene oxide (RGO) substrate. This breakthrough in design leads to the formation of interfacial Mo-S-C bonds and complete spin polarization of Mo 4d electrons near the Fermi level, potentially opening up a possibility for tailoring the magnetism of other 2D materials.
Article
Chemistry, Multidisciplinary
Wenjuan Yao, Lei Fan
Summary: This study investigates the interface thermal conductivity of graphene/h-BN planar heterostructure and explores the influence of external and internal fields on the formation and thermal conductivity of the structure. The results show that various factors, such as external force, defect number, and interface bonding morphology, affect the interface thermal conductivity.
Article
Nanoscience & Nanotechnology
Xin Wu, Qiang Han
Summary: This study systematically investigated the phonon thermal transport across multilayer Gr/h-BN vdW heterostructures, revealing important findings on the structural configuration and external modulation at the Gr/h-BN interface. It uncovers the physical mechanisms underlying the changes in the interfacial thermal conductance (ITC) and suggests directions for its modulation.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Multidisciplinary Sciences
Zainab Gholami, Farhad Khoeini
Summary: This paper investigates spin caloritronic effects in defected graphene/silicene nanoribbon (GSNR) junctions, showing that GSNRs with DV defects can provide almost perfect thermal spin filtering effect, negative differential thermoelectric resistance and high spin polarization efficiency.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Multidisciplinary
Pavel Valencia-Acuna, Fatimah Rudayni, Kushal Rijal, Wai-Lun Chan, Hui Zhao
Summary: We report the generation of long-lived and highly mobile photocarriers in hybrid van der Waals heterostructures that consist of monolayer graphene, few-layer transition metal dichalcogenides, and the organic semiconductor F8ZnPc. Photocarriers in the heterostructures can achieve long recombination lifetimes and high mobility by transferring electrons from F8ZnPc to graphene and separating them from the holes in F8ZnPc. The use of these artificial heterostructures can enhance the performance of graphene-based optoelectronic devices.
Article
Thermodynamics
Yixuan Xue, Harold S. Park, Jin-Wu Jiang
Summary: In this study, we demonstrate that the interfacial thermal resistance in graphene/fullerene/graphene sandwiches can be switchable and show a step-like change by varying the number of fullerenes. This switchable phenomenon is achieved by a structural transition between the graphene layers. The study also shows that mechanical strain or temperature variation can achieve the same switchable effect. This work highlights the potential application of sandwich-like nanoscale heterostructures in switchable thermal devices.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Chemistry, Multidisciplinary
Wenping Yin, Hanchen Li, Anthony S. R. Chesman, Ben Tadgell, Andrew D. Scully, Mingchao Wang, Wenchao Huang, Christopher R. McNeill, Wallace W. H. Wong, Nikhil Medhekar, Paul Mulvaney, Jacek J. Jasieniak
Summary: This research introduces a method for the selective and sensitive detection of halomethanes using photoluminescence spectral shifts in cesium lead halide perovskite nanocrystals. The approach allows for rapid and accurate detection of halomethanes, with high sensitivity and selectivity.
Article
Chemistry, Multidisciplinary
Sayantan Ghosh, Abin Varghese, Himani Jawa, Yuefeng Yin, Nikhil Medhekar, Saurabh Lodha
Summary: This study explores the use of WSe2/SnSe2 type-III structures in photodetectors, showing high negative responsivity and fast response time with controllable photocurrent polarity. By adjusting the band alignment from type-II to type-III, a significant enhancement in responsivity can be achieved, further supported by density functional theory calculations.
Article
Chemistry, Multidisciplinary
Qingdong Lin, Stefano Bernardi, Babar Shabbir, Qingdong Ou, Mingchao Wang, Wenping Yin, Shiqi Liu, Anthony S. R. Chesman, Sebastian O. Furer, Guangyuan Si, Nikhil Medhekar, Jacek Jasieniak, Asaph Widmer-Cooper, Wenxin Mao, Udo Bach
Summary: This study demonstrates a method for controlling the crystallization of inorganic cesium lead halide perovskite microstructures, successfully tuning the structure of perovskite crystals from 0D to 2D to 3D by adjusting the water to dimethylsulfoxide ratios.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Zhuoxin Li, Xing Li, Mingchao Wang, Molang Cai, Xiaoqiang Shi, Yaqi Mo, Xianggang Chen, Dongxu Ren, Miao Yang, Xuepeng Liu, Rui Jia, Nikhil Medhekar, Songyuan Dai
Summary: By introducing ammonium thiocyanate as a bifunctional additive into the precursor solution, the conversion efficiency and stability of tin-based perovskite solar cells were significantly improved in this study, with the PCE increasing from 4.45% to 8.15%. The modified perovskite film exhibited better film quality and superior environmental stability.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Himani Jawa, Abin Varghese, Sayantan Ghosh, Srilagna Sahoo, Yuefeng Yin, Nikhil Medhekar, Saurabh Lodha
Summary: This report demonstrates visible-to-near infrared wavelength-driven negative photoconductance (NPC) and positive photoconductance (PPC), along with reversible switching between the two. A few layer MoS2 flake covered on a broadband black phosphorus field effect transistor is used to achieve this, with the crossover switching wavelength and photoresponsivities modulated by varying the MoS2 bandgap through its flake thickness and electrostatic gating.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Qile Li, Chi Xuan Trang, Weikang Wu, Jinwoong Hwang, David Cortie, Nikhil Medhekar, Sung-Kwan Mo, Shengyuan A. Yang, Mark T. Edmonds
Summary: Combining magnetism and nontrivial band topology can achieve the quantum anomalous Hall (QAH) effect at high temperatures for lossless transport applications. In this study, a heterostructure consisting of two single-septuple layers (1SL) of MnBi2Te4, an ultrathin few quintuple layer (QL) Bi2Te3, and another 1SL MnBi2Te4 was grown via molecular beam epitaxy. The electronic structure was probed using angle-resolved photoelectron spectroscopy, and strong hexagonally warped massive Dirac fermions and a bandgap of 75 +/- 15 meV were observed. The magnetic origin of the gap was confirmed, and these findings provide insights into magnetic proximity effects in topological insulators and a promising platform for realizing the QAH effect at elevated temperatures.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
Tao Jiang, Hao Min, Renmeng Zou, Mingchao Wang, Kaichuan Wen, Jingya Lai, Lei Xu, Ying Wang, Wenjie Xu, Chengcheng Wang, Kang Wei, Nikhil Medhekar, Qiming Peng, Jin Chang, Wei Huang, Jianpu Wang
Summary: The dipole moment of the bulky cation is found to be an important factor controlling the distribution and crystallinity of different quantum wells in quasi-2D perovskites. Bulky cations with moderate dipole moment can lead to moderately distributed well-width MQWs and achieve favorable optical and electronic properties, resulting in improved device efficiency.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Abin Varghese, Yuefeng Yin, Mingchao Wang, Saurabh Lodha, Nikhil Medhekar
Summary: By conjugating with low-dimensional materials, such as transition metal dichalcogenides, ultrathin 2D perovskites can be extended to various visible-range photophysical applications. The bandgaps, carrier effective masses, and band offsets can be widely tuned to achieve effective separation of photogenerated excitons, enhancing the performance of photodetection and photovoltaic applications.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Chen-Chen Er, Lutfi K. Putri, Boon-Junn Ng, Jie-Yinn Tang, Nikhil V. Medhekar, Siang-Piao Chai
Summary: Controlling the product selectivity of CO2 photoreduction through allotropism is a promising strategy. In this study, three phosphorus allotropes were modeled as CO2 reduction photocatalysts and their CO2 adsorption behavior was investigated. It was found that each allotrope exhibits different selectivity towards C1 products due to their distinct p-band centers.
MATERIALS TODAY PHYSICS
(2022)
Article
Chemistry, Physical
Mingchao Wang, Han Ye, Vallabh Vasudevan, Nikhil Medhekar
Summary: This study investigates the thermodynamic and electrochemical performance of layered material MoS2 as a cathode for Mg-ion batteries using first-principles calculations. The findings show that increasing the interlayer spacing can enhance Mg diffusivities and specific capacity, but reduce electrode voltages.
JOURNAL OF POWER SOURCES
(2022)
Article
Physics, Applied
Chen-Chen Er, Lutfi K. Putri, Nikhil Medhekar, Siang-Piao Chai
Summary: Enhancement of carbon nitride through single transition metal atom modification improves its photocatalytic performance, with Pd and Cu identified as the most promising candidates for CO2 reduction.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Bernard Field, Agustin Schiffrin, Nikhil Medhekar
Summary: This study demonstrates how substrates influence the magnetic phases in kagome MOFs, taking into account factors such as MOF-substrate coupling, MOF-substrate charge transfer, strain, and external electric fields. The findings provide useful predictions for studying tunable interaction-induced magnetism in surface-supported 2D (metal-)organic materials.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Shenghan Su, Laure Bourgeois, Nikhil V. Medhekar
Summary: The high strength of structural aluminium alloys is due to the controlled precipitation of specific intermetallic phases. In this study, we investigate the AlPt system and design a workflow to predict the thermodynamics of various phases and their precipitation sequence in binary alloying systems. Our findings suggest that Al2Pt will precipitate first and form bulk-like interfaces similar to Al2Au rather than Al2Cu.
Article
Chemistry, Multidisciplinary
Motomi Aoki, Yuefeng Yin, Simon Granville, Yao Zhang, Nikhil V. Medhekar, Livio Leiva, Ryo Ohshima, Yuichiro Ando, Masashi Shiraishi
Summary: Co2MnGa, a topological quantum material with high structural symmetry, exhibits a gigantic anisotropy of self-induced spin-orbital torque (SOT), which is a result of the interplay between the topological nature of the electronic states and external strain.
Article
Materials Science, Multidisciplinary
Yuefeng Yin, Chutian Wang, Michael S. Fuhrer, Nikhil Medhekar
Summary: Tuning the interaction between the bulk and edge states of topological materials is a powerful tool for manipulating edge transport behavior in planar bismuthene. By exploring the impact of various perturbation effects, such as device size, substrate potentials, and applied transverse electric field, the electronic structure and edge transport in planar bismuthene can be engineered to exhibit either a gapped or conducting unconventional helical spin texture. These results open up new directions for discovering novel spin transport patterns in topological materials and provide critical insights for the fabrication of topological spintronic devices.
MATERIALS TODAY PHYSICS
(2023)
