Ravi Yadav, Lei Xu, Michele Pizzochero, Jeroen van den Brink, Mikhail I. Katsnelson, Oleg V. Yazyev
{"title":"Electronic excitations and spin interactions in chromium trihalides from embedded many-body wavefunctions","authors":"Ravi Yadav, Lei Xu, Michele Pizzochero, Jeroen van den Brink, Mikhail I. Katsnelson, Oleg V. Yazyev","doi":"10.1038/s41699-024-00494-5","DOIUrl":"10.1038/s41699-024-00494-5","url":null,"abstract":"Although chromium trihalides are widely regarded as a promising class of two-dimensional magnets for next-generation devices, an accurate description of their electronic structure and magnetic interactions has proven challenging to achieve. Here, we quantify electronic excitations and spin interactions in CrX3 (X = Cl, Br, I) using embedded many-body wavefunction calculations and fully generalized spin Hamiltonians. We find that the three trihalides feature comparable d-shell excitations, consisting of a high-spin 4A2 $$({t}_{2g}^{3}{e}_{g}^{0})$$ ground state lying 1.5–1.7 eV below the first excited state 4T2 ( $${t}_{2g}^{2}{e}_{g}^{1}$$ ). CrCl3 exhibits a single-ion anisotropy Asia = − 0.02 meV, while the Cr spin-3/2 moments are ferromagnetically coupled through bilinear and biquadratic exchange interactions of J1 = − 0.97 meV and J2 = − 0.05 meV, respectively. The corresponding values for CrBr3 and CrI3 increase to Asia = −0.08 meV and Asia= − 0.12 meV for the single-ion anisotropy, J1 = −1.21 meV, J2 = −0.05 meV and J1 = −1.38 meV, J2 = −0.06 meV for the exchange couplings, respectively. We find that the overall magnetic anisotropy is defined by the interplay between Asia and Adip due to magnetic dipole–dipole interaction that favors in-plane orientation of magnetic moments in ferromagnetic monolayers and bulk layered magnets. The competition between the two contributions sets CrCl3 and CrI3 as the easy-plane (Asia + Adip >0) and easy-axis (Asia + Adip <0) ferromagnets, respectively. The differences between the magnets trace back to the atomic radii of the halogen ligands and the magnitude of spin–orbit coupling. Our findings are in excellent agreement with recent experiments, thus providing reference values for the fundamental interactions in chromium trihalides.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.1,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00494-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142091215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Md. Anamul Hoque, Antony George, Vasudev Ramachandra, Emad Najafidehaghani, Ziyang Gan, Richa Mitra, Bing Zhao, Satyaprakash Sahoo, Maria Abrahamsson, Qiuhua Liang, Julia Wiktor, Andrey Turchanin, Sergey Kubatkin, Samuel Lara-Avila, Saroj P. Dash
{"title":"All-2D CVD-grown semiconductor field-effect transistors with van der Waals graphene contacts","authors":"Md. Anamul Hoque, Antony George, Vasudev Ramachandra, Emad Najafidehaghani, Ziyang Gan, Richa Mitra, Bing Zhao, Satyaprakash Sahoo, Maria Abrahamsson, Qiuhua Liang, Julia Wiktor, Andrey Turchanin, Sergey Kubatkin, Samuel Lara-Avila, Saroj P. Dash","doi":"10.1038/s41699-024-00489-2","DOIUrl":"10.1038/s41699-024-00489-2","url":null,"abstract":"Two-dimensional (2D) semiconductors and van der Waals (vdW) heterostructures with graphene have generated enormous interest for future electronic, optoelectronic, and energy-harvesting applications. The electronic transport properties and correlations of such hybrid devices strongly depend on the quality of the materials via chemical vapor deposition (CVD) process, their interfaces and contact properties. However, detailed electronic transport and correlation properties of the 2D semiconductor field-effect transistor (FET) with vdW graphene contacts for understanding mobility limiting factors and metal-insulator transition properties are not explored. Here, we investigate electronic transport in scalable all-2D CVD-grown molybdenum disulfide (MoS2) FET with graphene contacts. The Fermi level of graphene can be readily tuned by a gate voltage to enable a nearly perfect band alignment and, hence, a reduced and tunable Schottky barrier at the contact with good field-effect channel mobility. Detailed temperature-dependent transport measurements show dominant phonon/impurity scattering as a mobility limiting mechanisms and a gate-and bias-induced metal-insulator transition in different temperature ranges, which is explained in light of the variable-range hopping transport. These studies in such scalable all-2D semiconductor heterostructure FETs will be useful for future electronic and optoelectronic devices for a broad range of applications.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-7"},"PeriodicalIF":9.1,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00489-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matthew D. Watson, Swagata Acharya, James E. Nunn, Laxman Nagireddy, Dimitar Pashov, Malte Rösner, Mark van Schilfgaarde, Neil R. Wilson, Cephise Cacho
{"title":"Giant exchange splitting in the electronic structure of A-type 2D antiferromagnet CrSBr","authors":"Matthew D. Watson, Swagata Acharya, James E. Nunn, Laxman Nagireddy, Dimitar Pashov, Malte Rösner, Mark van Schilfgaarde, Neil R. Wilson, Cephise Cacho","doi":"10.1038/s41699-024-00492-7","DOIUrl":"10.1038/s41699-024-00492-7","url":null,"abstract":"We present the evolution of the electronic structure of CrSBr from its antiferromagnetic ground state to the paramagnetic phase above TN = 132 K, in both experiment and theory. Low-temperature angle-resolved photoemission spectroscopy (ARPES) results are obtained using a novel method to overcome sample charging issues, revealing quasi-2D valence bands in the ground state. The results are very well reproduced by our $${rm{QSG}}hat{{rm{W}}}$$ calculations, which further identify certain bands at the X points to be exchange-split pairs of states with mainly Br and S character. By tracing band positions as a function of temperature, we show the splitting disappears above TN. The energy splitting is interpreted as an effective exchange splitting in individual layers in which the Cr moments all align, within the so-called A-type antiferromagnetic arrangement. Our results lay firm foundations for the interpretation of the many other intriguing physical and optical properties of CrSBr.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.1,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00492-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amira Bencherif, Monique Tie, Richard Martel, Delphine Bouilly
{"title":"Automated and parallel transfer of arrays of oriented graphene ribbons","authors":"Amira Bencherif, Monique Tie, Richard Martel, Delphine Bouilly","doi":"10.1038/s41699-024-00491-8","DOIUrl":"10.1038/s41699-024-00491-8","url":null,"abstract":"The transfer of two-dimensional materials from their growth substrate onto application wafers is a critical bottleneck in scaling-up devices based on such nanomaterials. Here, we present an innovative approach to achieve the automated and simultaneous transfer of arrays of graphene ribbons, with precise control over their orientation and alignment onto patterned wafers. The transfer is performed in a simple, yet efficient apparatus consisting of an array of glass columns, strategically shaped to control ribbon orientation and arranged to match the destination wafer, coupled to a dual inflow/outflow pumping system. This apparatus enables the transfer of a custom array of parallel graphene ribbons in a fraction of the time required with traditional methods. The quality of the transferred graphene was evaluated using optical imaging, scanning electron microscopy, hyperspectral Raman imaging, and electrical transport: all consistently indicating that the transferred graphene exhibits excellent quality, comparable to a manual transfer by an expert user. The proposed apparatus offers several competitive advantages, including ease of use, high transfer throughput, and reduced nanomaterial consumption. Moreover, it can be used repeatedly on the same wafer to assemble arrays of overlayed materials with controlled relative orientations. This approach thus opens promising opportunities for the large-scale fabrication of various heterostructures and devices based on vertical assemblies of 2D nanomaterials.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-9"},"PeriodicalIF":9.1,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00491-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Tkáč, S. Vorobiov, P. Baloh, M. Vondráček, G. Springholz, K. Carva, P. Szabó, Ph. Hofmann, J. Honolka
{"title":"Multiphase superconductivity at the interface between ultrathin FeTe islands and Bi2Te3","authors":"V. Tkáč, S. Vorobiov, P. Baloh, M. Vondráček, G. Springholz, K. Carva, P. Szabó, Ph. Hofmann, J. Honolka","doi":"10.1038/s41699-024-00480-x","DOIUrl":"10.1038/s41699-024-00480-x","url":null,"abstract":"FeTe monolayer islands situated on a topological insulator Bi2Te3 (0001) surface were recently reported to exhibit the opening of an energy gap below temperatures T ~ 6 K, which could be due to a superconducting phase transition. In this work, we present a magnetic field dependent transport study proving that this gap is indeed of superconducting origin. Upon cooling, several drops in resistance are observed in the temperature range between 6 K and 2 K, indicating multiple transitions. Using the Ginzburg-Landau theory, we show that the critical magnetic field of the dominant high-temperature transition at ~ 6 K is governed by orbital Cooper pair breaking in larger FeTe islands, large enough to exceed the superconductive coherence length $$xi$$ . At smaller island sizes, transitions at lower temperatures < 6 K become more prominent, showing significantly increased critical fields dominated by paramagnetic pair breaking. The multiphase superconducting behaviour is in line with an observed wide distribution of FeTe islands width 5–100 nm and seems to reflect disorder effects at the interface to Bi2Te3. The proof of local superconductivity makes the FeTe interface to the topological insulator Bi2Te3 substrate a potential host of topological superconductivity.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00480-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fengyi Zhou, Monirul Shaikh, Weiwei Sun, Feng Chen, Xin Chen, Shu Li, Henry Tong, Biplab Sanyal, Duo Wang
{"title":"Emergence of polar skyrmions in 2D Janus CrInX3 (X=Se, Te) magnets","authors":"Fengyi Zhou, Monirul Shaikh, Weiwei Sun, Feng Chen, Xin Chen, Shu Li, Henry Tong, Biplab Sanyal, Duo Wang","doi":"10.1038/s41699-024-00490-9","DOIUrl":"10.1038/s41699-024-00490-9","url":null,"abstract":"In the realm of multiferroicity in 2D magnets, whether magnetic and polar skyrmions can coexist within a single topological entity has emerged as an important question. Here, we study Janus 2D magnets CrInX3 (X=Se, Te) for a comprehensive investigation of the magnetic ground state, magnetic excited state, and corresponding ferroelectric polarization by first-principles electronic structure calculations and Monte Carlo simulations. Specifically, we have thoroughly elucidated the magnetic exchange mechanisms, and have fully exemplified the magnetic field dependence of the magnon spectrum. More importantly, our study reveals a previously unrecognized, remarkably large spin-spiral-induced ferroelectric polarization (up to 194.9 μC/m2) in both compounds. We propose an approach to identify polar skyrmions within magnetic skyrmions, based on the observed direct correlation between spin texture and polarization density. Elucidating this correlation not only deepens our understanding of magnetic skyrmions but also paves the way for innovative research in the realm of multiferroic skyrmions.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-12"},"PeriodicalIF":9.1,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00490-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amir Kleiner, Daniel Hernangómez-Pérez, Sivan Refaely-Abramson
{"title":"Designable exciton mixing through layer alignment in WS2-graphene heterostructures","authors":"Amir Kleiner, Daniel Hernangómez-Pérez, Sivan Refaely-Abramson","doi":"10.1038/s41699-024-00484-7","DOIUrl":"10.1038/s41699-024-00484-7","url":null,"abstract":"Optical properties of heterostructures composed of layered 2D materials, such as transition metal dichalcogenides (TMDs) and graphene, are broadly explored. Of particular interest are light-induced energy transfer mechanisms in these materials and their structural roots. Here, we use state-of-the-art first-principles calculations to study the excitonic composition and the absorption properties of WS2–graphene heterostructures as a function of interlayer alignment and the local strain resulting from it. We find that Brillouin zone mismatch and the associated energy level alignment between the graphene Dirac cone and the TMD bands dictate an interplay between interlayer and intralayer excitons, mixing together in the many-body representation upon the strain-induced symmetry breaking in the interacting layers. Examining the representative cases of the 0° and 30° interlayer twist angles, we find that this exciton mixing strongly varies as a function of the relative alignment. We quantify the effect of these structural modifications on exciton charge separation between the layers and the associated graphene-induced homogeneous broadening of the absorption resonances. Our findings provide guidelines for controllable optical excitations upon interface design and shed light on the importance of many-body effects in the understanding of optical phenomena in complex heterostructures.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-7"},"PeriodicalIF":9.1,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00484-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chirag Chandrakant Palekar, Paulo E. Faria Junior, Barbara Rosa, Frederico B. Sousa, Leandro M. Malard, Jaroslav Fabian, Stephan Reitzenstein
{"title":"Amplification of interlayer exciton emission in twisted WSe2/WSe2/MoSe2 heterotrilayers","authors":"Chirag Chandrakant Palekar, Paulo E. Faria Junior, Barbara Rosa, Frederico B. Sousa, Leandro M. Malard, Jaroslav Fabian, Stephan Reitzenstein","doi":"10.1038/s41699-024-00483-8","DOIUrl":"10.1038/s41699-024-00483-8","url":null,"abstract":"Van der Waals heterostructures based on transition metal dichalcogenides exhibit physical properties that depend on their monolayer constituents’ twisting angle and stacking order. Particularly in type-II heterostructures, low-energy photoluminescence is dominated by interlayer excitons, resulting in low emission yields, which drastically hampers their optoelectronic applicability. This study reports on the photoluminescence quantum yield of heterostructures consisting of WSe2/WSe2/MoSe2 twisted layers. Our findings show that the additional WSe2 monolayer in the trilayer system enhances the low-energy photoluminescence by more than an order of magnitude depending on the WSe2/WSe2 twist-angle in comparison to their WSe2/MoSe2 heterobilayer counterpart. Furthermore, combining density functional theory calculations and extracted degree of circular polarization, we identify excitonic signatures arising from hybridized states that originate from the additional WSe2 layer. In addition to providing an additional understanding of hybridization effects in 2D semiconducting heterostructures, our findings provide a viable method to enhance emission in van der Waals heterostructures, relevant for studying the fundamental properties of excitons and enabling optoelectronic applications with high luminescence yield.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-8"},"PeriodicalIF":9.1,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00483-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gyula Halasi, Csaba Vass, Ka Man Yu, Gábor Vári, Arnold P. Farkas, Krisztián Palotás, András Berkó, János Kiss, Zoltán Kónya, Martin Aeschlimann, Benjamin Stadtmüller, Péter Dombi, László Óvári
{"title":"Enhancing the dipole ring of hexagonal boron nitride nanomesh by surface alloying","authors":"Gyula Halasi, Csaba Vass, Ka Man Yu, Gábor Vári, Arnold P. Farkas, Krisztián Palotás, András Berkó, János Kiss, Zoltán Kónya, Martin Aeschlimann, Benjamin Stadtmüller, Péter Dombi, László Óvári","doi":"10.1038/s41699-024-00487-4","DOIUrl":"10.1038/s41699-024-00487-4","url":null,"abstract":"Surface templating by electrostatic surface potentials is the least invasive way to design large-scale artificial nanostructures. However, generating sufficiently large potential gradients remains challenging. Here, we lay the groundwork for significantly enhancing local electrostatic fields by chemical modification of the surface. We consider the hexagonal boron nitride (h-BN) nanomesh on Rh(111), which already exhibits small surface potential gradients between its pore and wire regions. Using photoemission spectroscopy, we show that adding Au atoms to the Rh(111) surface layer leads to a local migration of Au atoms below the wire regions of the nanomesh. This significantly increases the local work function difference between the pore and wire regions that can be quantified experimentally by the changes in the h-BN valence band structure. Using density functional theory, we identify an electron transfer from Rh to Au as the microscopic origin for the local enhancement of potential gradients within the h-BN nanomesh.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-10"},"PeriodicalIF":9.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00487-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141775086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Manikandan, S. Karishma, Mukesh Kumar, Pramoda K. Nayak
{"title":"Salinity gradient induced blue energy generation using two-dimensional membranes","authors":"D. Manikandan, S. Karishma, Mukesh Kumar, Pramoda K. Nayak","doi":"10.1038/s41699-024-00486-5","DOIUrl":"10.1038/s41699-024-00486-5","url":null,"abstract":"Salinity gradient energy (SGE), known as blue energy is harvested from mixing seawater with river water in a controlled way using ion exchange membranes (IEMs). Using 2D materials as IEMs improves the output power density from a few Wm−2 to a few thousands of Wm−2 over conventional membranes. In this review, we survey the efforts taken to employ the different 2D materials as nanoporous or lamellar membranes for SGE and provide a comprehensive analysis of the fundamental principles behind the SGE. Overall, this review is anticipated to explain how the 2D materials can make SGE a viable source of energy.","PeriodicalId":19227,"journal":{"name":"npj 2D Materials and Applications","volume":" ","pages":"1-19"},"PeriodicalIF":9.1,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41699-024-00486-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141785348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}