Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platf...Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platform for the exploration of novel quantum phenomena and materials applications.Particularly exciting is the exploration of nonequilibrium dynamics in quantum materials,which has significant research and potential application values.Pump-probe techniques play a key role in revealing the dynamics of quantum materials on remarkably short timescales,providing an attractive yet challenging avenue of research.In this context,time-resolved x-ray as an emerging probe exhibits high time resolution,momentum resolution,and substantial momentum coverage.It can reveal unprecedented transient states,distinguish between entangled ordered states,and has a compelling potential to probe ultrafast dynamics in a wide variety of quantum materials.Despite its unique advantages,time-resolved x-ray scattering still faces several technological and methodological challenges.In this review,we highlight recent advances focusing on the use of time-resolved x-ray scattering to probe dynamic processes in quantum materials.We discuss representative examples across structural,electronic,magnetic,and lattice degrees of freedom,and outline promising directions for future research in this rapidly evolving field.展开更多
Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed ...Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed matter physics.Currently,it has been found that there are two interesting systems in topological quantum materials:topological superconducting materials and topological magnetic materials.Although research on these materials has made rapid progress,a systematic review of their synthesis,properties,and applications,particularly their synthesis,is still lacking.In this paper,we emphasize the experimental preparation of two typical topological quantum materials and then briefly introduce their potential physical properties and applications.Finally,we provide insights into current and future issues in the study of topological quantum material systems.展开更多
Moiré superlattices have revolutionized the study of two-dimensional materials, enabling unprecedented control over their electronic, magnetic, optical, and mechanical properties. This review provides a comprehen...Moiré superlattices have revolutionized the study of two-dimensional materials, enabling unprecedented control over their electronic, magnetic, optical, and mechanical properties. This review provides a comprehensive analysis of the latest advancements in moiré physics, focusing on the formation of moiré superlattices due to rotational misalignment or lattice mismatch in two-dimensional materials. These superlattices induce flat band structures and strong correlation effects,leading to the emergence of exotic quantum phases, such as unconventional superconductivity, correlated insulating states,and fractional quantum anomalous Hall effects. The review also explores the underlying mechanisms of these phenomena and discusses the potential technological applications of moiré physics, offering insights into future research directions in this rapidly evolving field.展开更多
Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural det...Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural details.While numerous intriguing physical properties have been revealed in recently discovered two-dimensional(2D)quantummaterials,many exhibit significant sensitivity towater and oxygen under ambient conditions.This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements.This review highlights recent technical advancements to preserve the intrinsic structures of water-and oxygen-sensitive 2D materials for atomic-scale characterizations.A critical development discussed in this review is implementing an inert gas-protected glovebox integrated system(GIS)designed specifically for TEM experiments.In addition,this review emphasizes air-sensitivematerials such as 2D transitionmetal dichalcogenides,transition metal dihalides and trihalides,and low-dimensional magnetic materials,demonstrating breakthroughs in overcoming their environmental sensitivity.Furthermore,the progress in TEM characterization enabled by the GIS is analyzed to provide a comprehensive overview of state-of-the-art methodologies in this rapidly advancing field.展开更多
The field of colloidal nanocrystals has witnessed enormous progress in the last three decades.For many families of nanocrystals,wet-chemical syntheses have been developed that allow control over the crystal shape and ...The field of colloidal nanocrystals has witnessed enormous progress in the last three decades.For many families of nanocrystals,wet-chemical syntheses have been developed that allow control over the crystal shape and dimensions,from the three-dimensional down to the zero-dimensional case.Additionally,careful control of surface chemistry has enabled the prevention of non-radiative recombination,thus allowing the detailed study of confined charge carriers and excitons.This has led to a vast amount of applications of nanocrystals in displays,labels,and lighting.Here,we discuss how this expertise could benefit the rapidly advancing field of quantum materials,where the coherence of electronic wave functions is key.We demonstrate that colloidal two-dimensional nanocrystals can serve as excellent model systems for studying topological phase transitions,particularly in the case of quantum spin Hall and topological crystalline insulators.We aim to inspire researchers with strong chemical expertise to explore the exciting field of quantum materials.展开更多
Transmission electron microscopy(TEM)offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures.However,high-energy imaging electrons can induce structural damage,posing a challeng...Transmission electron microscopy(TEM)offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures.However,high-energy imaging electrons can induce structural damage,posing a challenge for electron-beam-sensitive materials.Cryogenic TEM(Cryo-TEM)has revolutionized structural biology,enabling the visualization of biomolecules in their near-native states at unprecedented detail.The low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum phenomena.Here,we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures,illustrating the electron beam-induced damage and the mitigating role of Cryo-TEM.This review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based materials.Furthermore,we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials,including the detection of charge order and novel topological spin textures.Finally,we discuss the future prospects of Cryo-TEM,emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.展开更多
Two-dimensional(2D)quantum materials have attracted extensive attention due to their superior properties at the atomic thickness.Numerous novel physical phenomena,including the quantum Hall effect,fractional quantum H...Two-dimensional(2D)quantum materials have attracted extensive attention due to their superior properties at the atomic thickness.Numerous novel physical phenomena,including the quantum Hall effect,fractional quantum Hall effect,quantum anomalous Hall effect and topological superconductor phase or topological insulator phase,have been discovered on different2D quantum materials.Over the past decades,various technologies have been developed to prepare the 2D quantum materials and all of them have demonstrated their specific advantages.In this review,we comprehensively summarize the commonly used growth methods for the 2D quantum materials and discuss the corresponding controllable growth strategies.Finally,we provide a summary and a perspective for future studies.展开更多
The search for and study of exotic quantum states in novel low-dimensional quantum materials have triggered extensive research in recent years. Here, we systematically study the electronic and magnetic structures in t...The search for and study of exotic quantum states in novel low-dimensional quantum materials have triggered extensive research in recent years. Here, we systematically study the electronic and magnetic structures in the newly discovered two-dimensional quantum material C3N within the framework of density functional theory. The calculations demonstrate that C3N is an indirect-band semiconductor with an energy gap of 0.38 eV, which is in good agreement with experimental observations. Inter- estingly, we find van Hove singularities located at energies near the Fermi level, which is half that of graphene. Thus, the Fermi energy easily approaches that of the singularities, driving the system to ferromagnetism, under charge carrier injection, such as electric field gating or hydrogen doping. These findings not only demonstrate that the emergence of magnetism stems from the itinerant electron mechanism rather than the effects of local magnetic impurities, but also open a new avenue to de- signing field-effect transistor devices for possible realization of an insulator-ferromagnet transition by tuning an external electric field.展开更多
Upon femtosecond laser excitation in quantum materials,it is possible to study the many-body interactions through the non-equilibrium processes,realize ultrafast electronic phase transitions,and achieve photoinduced n...Upon femtosecond laser excitation in quantum materials,it is possible to study the many-body interactions through the non-equilibrium processes,realize ultrafast electronic phase transitions,and achieve photoinduced novel states or hidden states.Such studies of the interaction between the ultrafast laser and the quantum materials are the frontiers and attract significant research interests in the field of condensed matter physics.Time-and angle-resolved photoemission spectroscopy is a key experimental tool to study the ultrafast electronic dynamics in quantum materials after photoexcitation.This paper reviews the development of a high-resolution time-and angle-resolved photoemission system based on nonlinear optical crystals and the studies on the ultrafast electronic dynamics in quantum materials using such a setup,including(1)probing the unoccupied electronic states in quantum materials,(2)photoinduced ultrafast electronic phase transitions,and(3)photoinduced new states of matter.展开更多
Interests in organic quantum materials(OQMs)have been explosively growing in the field of condensed physics of matter due to their rich chemistry and unique quantum properties.They are strongly correlated systems and ...Interests in organic quantum materials(OQMs)have been explosively growing in the field of condensed physics of matter due to their rich chemistry and unique quantum properties.They are strongly correlated systems and show novel electromagnetic performance such as high-temperature superconducting,quantum sensing,spin electronics,quantum dots,topological insulating,quantum Hall effects,spin liquids,qubits,and so forth,which exhibit promising prospects in information communication and thus facilitate the construction of a modern intelligent society.This article reviews recent developments in the research on the electromagnetic characteristics of OQMs.We mainly give an overview on the progress of superconductors and quantum spin liquids based on organic materials and describe their possible mechanisms.Numerous experimental findings exhibit new exciton interactions and provide insights into exotic electronic properties.Finally,their association and strategies for realizing multiple quantum states in one system are discussed.展开更多
In recent years,topological quantum materials(TQMs)have attracted intensive attention in the area of condensed matter physics due to their novel topologies and their promising applications in quantum computing,spin el...In recent years,topological quantum materials(TQMs)have attracted intensive attention in the area of condensed matter physics due to their novel topologies and their promising applications in quantum computing,spin electronics and next-generation integrated circuits.Scanning tunneling microscopy/spectroscopy(STM/STS)is regarded as a powerful technique to characterize the local density of states with atomic resolution,which is ideally suited to the measurement of the bulk-boundary correspondence of TQMs.In this review,using STM/STS,we focus on recent research on bismuth-based TQMs,including quantum-spin Hall insulators,3D weak topological insulators(TIs),high-order TIs,topological Dirac semi-metals and dual TIs.Efficient methods for the modulation of the topological properties of the TQMs are introduced,such as interlayer interaction,thickness variation and local electric field perturbation.Finally,the challenges and prospects for this field of study are discussed.展开更多
Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin ...Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.展开更多
Two novel organic hole-transporting materials have been synthesized by combination of triphenylamines（TPA） viaπ-conjugated bonds using Wittig reaction.The structures were characterized by NMR,FT-IR and HRMS.The opt...Two novel organic hole-transporting materials have been synthesized by combination of triphenylamines（TPA） viaπ-conjugated bonds using Wittig reaction.The structures were characterized by NMR,FT-IR and HRMS.The optical,electrochemical and thermal properties of the materials were studied in detail.The results show that these two compounds have blue emission,proper HOMO levels and high thermal stability.Furthermore,a quantum chemical calculation on electron distribution of the two compounds was performed, which suggests the current synthesized materials would be promising candidates for hole-transporting materials.展开更多
Heat transport is a key energetic process in materials and devices. The reduced sample size, low dimension of the problem and the rich spectrum of material imperfections introduce fruitful phenomena at nanoscale. In t...Heat transport is a key energetic process in materials and devices. The reduced sample size, low dimension of the problem and the rich spectrum of material imperfections introduce fruitful phenomena at nanoscale. In this review, we summarize recent progresses in the understanding of heat transport process in low-dimensional materials, with focus on the roles of defects, disorder, interfaces, and the quantum- mechanical effect. New physics uncovered from computational simulations, experimental studies, and predictable models will be reviewed, followed by a perspective on open challenges.展开更多
Due to the influence of quantum confinementeffect, two-dimensional (2D) materials like graphene exhibitunique and exceptional properties, highlighting the significance of low-dimensional materials in fundamental resea...Due to the influence of quantum confinementeffect, two-dimensional (2D) materials like graphene exhibitunique and exceptional properties, highlighting the significance of low-dimensional materials in fundamental research and practical applications. This has led to highexpectations for one-dimensional (1D) atomic chain materialswith even lower dimensions. Compared with 2D materials,single 1D atomic chains reach their physical limits in bothdimensions, resulting in a more pronounced quantum confinement effect that gives rise to unexpected physical phenomena and will establish a new field for exploration. Herein,we review the emerging field concerning 1D van der Waals(vdW) atomic chains. We first summarize the various typesand structures of their bulk of the 1D vdW materials. Subsequently,we discuss the methods employed for their preparation and characterization. Finally, we analyze the challengesfaced during the development of 1D atomic chains and provide prospects for their future development.展开更多
The rare-earth nickelates(RENiO_(3)) exhibit an exceptional complex electronic phase diagram and multiple electronic phase transitions that enrich promising applications in correlated electronic devices beyond convent...The rare-earth nickelates(RENiO_(3)) exhibit an exceptional complex electronic phase diagram and multiple electronic phase transitions that enrich promising applications in correlated electronic devices beyond conventional semiconductors.Nevertheless,the practical applications of RENiO_(3) are challenged by their intrinsic thermodynamic metastability in material synthesis and high material cost.Therefore,developing an economical strategy to achieve the batch synthesis of RENiO_(3) is of vital importance.In this work,we enlarged the synthesis amount of RENiO_(3) up to 20 g per batch using chloride(KCI) assisted molten salt reaction.By optimizing the reaction conditions,the powder of RENiO_(3) with the cubic shape and average size of ~2μm was effectively synthesized,while their phase purity exceeded 95%.In addition,the cost to synthesize RENiO_(3) was further reduced by using rare-earth extraction intermediate products as the raw materials,instead of using the pure rare-earth precursors.It also achieved wide adjustments in the metal-to-insulator-transition temperature from160 to 420 K without significantly reducing the transition sharpness.By enlarging the synthesis amount and the reducing the cost,it paves the way to the device application of RENiO_(3).展开更多
Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has b...Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has become particularly important.However,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation Facility.The beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 eV.In addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.展开更多
Two-dimensional(2D)materials showcase great potentials in both fundamental research and technology development,thanks to their unique chemical and physical properties that are usually not available in corresponding bu...Two-dimensional(2D)materials showcase great potentials in both fundamental research and technology development,thanks to their unique chemical and physical properties that are usually not available in corresponding bulk counterparts.As an emerging class of 2D materials,2D conductive metal-organic frameworks(2D c-MOFs)exhibit the characteristics of pre-designable and tunable structures,excellent crystallinity,intrinsic porosity and superior conductivity.During the past decade,2D c-MOFs have been rapidly developed in electronics,sensors,energy storage devices,etc.In this review,the electrical,magnetic and quantum properties of 2D c-MOFs are surveyed in detail.Their applications in semiconductor,metal,superconductor,topological insulator and porous magnet are highlighted.We envision that the combination of 2D c-MOFs with quantum materials could evoke rich physics,flexible chemistry and potential applications in both electronics and spintronics.展开更多
基金the National Key R&D Program of China(Grants Nos.2024YFA1408702 and 2021YFA1401903)Beijing Natural Science Foundation(Grant No.JQ24001)the National Natural Science Foundation of China(Grant No.12374143)。
文摘Quantum materials have attracted a great deal of attention because of their rich landscape of electronic structures,topological phases,strong correlation effects,and exotic orders.These systems provide a fertile platform for the exploration of novel quantum phenomena and materials applications.Particularly exciting is the exploration of nonequilibrium dynamics in quantum materials,which has significant research and potential application values.Pump-probe techniques play a key role in revealing the dynamics of quantum materials on remarkably short timescales,providing an attractive yet challenging avenue of research.In this context,time-resolved x-ray as an emerging probe exhibits high time resolution,momentum resolution,and substantial momentum coverage.It can reveal unprecedented transient states,distinguish between entangled ordered states,and has a compelling potential to probe ultrafast dynamics in a wide variety of quantum materials.Despite its unique advantages,time-resolved x-ray scattering still faces several technological and methodological challenges.In this review,we highlight recent advances focusing on the use of time-resolved x-ray scattering to probe dynamic processes in quantum materials.We discuss representative examples across structural,electronic,magnetic,and lattice degrees of freedom,and outline promising directions for future research in this rapidly evolving field.
基金supported by National Natural Science Foundation of China(52373309).
文摘Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed matter physics.Currently,it has been found that there are two interesting systems in topological quantum materials:topological superconducting materials and topological magnetic materials.Although research on these materials has made rapid progress,a systematic review of their synthesis,properties,and applications,particularly their synthesis,is still lacking.In this paper,we emphasize the experimental preparation of two typical topological quantum materials and then briefly introduce their potential physical properties and applications.Finally,we provide insights into current and future issues in the study of topological quantum material systems.
基金Project supported by the National Key R&D Program of China (Grant No. 2019YFA0307800)the National Natural Science Foundation of China (Grant No. 12074377)+2 种基金Fundamental Research Funds for the Central Universities,the International Partnership Program of Chinese Academy of Sciences (Grant No. 211211KYSB20210007)the China Postdoctoral Science Foundation (Grant No. 2024M753465)the Postdoctoral Fellowship Program (Grade C) of China Postdoctoral Science Foundation (Grant No. GZC20241893)。
文摘Moiré superlattices have revolutionized the study of two-dimensional materials, enabling unprecedented control over their electronic, magnetic, optical, and mechanical properties. This review provides a comprehensive analysis of the latest advancements in moiré physics, focusing on the formation of moiré superlattices due to rotational misalignment or lattice mismatch in two-dimensional materials. These superlattices induce flat band structures and strong correlation effects,leading to the emergence of exotic quantum phases, such as unconventional superconductivity, correlated insulating states,and fractional quantum anomalous Hall effects. The review also explores the underlying mechanisms of these phenomena and discusses the potential technological applications of moiré physics, offering insights into future research directions in this rapidly evolving field.
基金supported by the National Key Basic Research and Development Program of China,China(No.2024YFA1409100)support by the National Natural Science Foundation of China,China(Nos.52473302 and 12461160252)+4 种基金Guangdong Innovative and Entrepreneurial Research Team Program,China(No.2019ZT08C044)Guangdong Basic Science Foundation,China(2023B1515120039)Shenzhen Science and Technology Program,China(No.20200925161102001)the Science,Technology and Innovation Commission of Shenzhen Municipality,China(No.ZDSYS20190902092905285)Quantum Science Strategic Special Project from the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area,China(No.GDZX2301006).
文摘Transmission electron microscopy(TEM)is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics,phase transitions,and nanoscale structural details.While numerous intriguing physical properties have been revealed in recently discovered two-dimensional(2D)quantummaterials,many exhibit significant sensitivity towater and oxygen under ambient conditions.This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements.This review highlights recent technical advancements to preserve the intrinsic structures of water-and oxygen-sensitive 2D materials for atomic-scale characterizations.A critical development discussed in this review is implementing an inert gas-protected glovebox integrated system(GIS)designed specifically for TEM experiments.In addition,this review emphasizes air-sensitivematerials such as 2D transitionmetal dichalcogenides,transition metal dihalides and trihalides,and low-dimensional magnetic materials,demonstrating breakthroughs in overcoming their environmental sensitivity.Furthermore,the progress in TEM characterization enabled by the GIS is analyzed to provide a comprehensive overview of state-of-the-art methodologies in this rapidly advancing field.
基金the research program“Materials for the Quantum Age”(QuMat)for financial supportprogram(registration number 024.005.006)is part of the Gravitation program financed by the Dutch Ministry of Education,Culture and Science(OCW).the ERC Consolidator Grant(Horizon 2020“FRACTAL”,Grant 865570)for financial help.The computer chip of the TOC figure was generated with DALL∙E 3 using the prompt:“Cartoon style green computer chip”.
文摘The field of colloidal nanocrystals has witnessed enormous progress in the last three decades.For many families of nanocrystals,wet-chemical syntheses have been developed that allow control over the crystal shape and dimensions,from the three-dimensional down to the zero-dimensional case.Additionally,careful control of surface chemistry has enabled the prevention of non-radiative recombination,thus allowing the detailed study of confined charge carriers and excitons.This has led to a vast amount of applications of nanocrystals in displays,labels,and lighting.Here,we discuss how this expertise could benefit the rapidly advancing field of quantum materials,where the coherence of electronic wave functions is key.We demonstrate that colloidal two-dimensional nanocrystals can serve as excellent model systems for studying topological phase transitions,particularly in the case of quantum spin Hall and topological crystalline insulators.We aim to inspire researchers with strong chemical expertise to explore the exciting field of quantum materials.
基金Project supported by the National Natural Science Foundation of China (Grant No.11974156)the Guangdong Innovative and Entrepreneurial Research Team Program (Grant No.2019ZT08C044)+1 种基金the Shenzhen Science and Technology Program (Grant Nos.KQTD20190929173815000 and 20200925161102001)the Science,Technology and Innovation Commission of Shenzhen Municipality (Grant No.ZDSYS20190902092905285)。
文摘Transmission electron microscopy(TEM)offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures.However,high-energy imaging electrons can induce structural damage,posing a challenge for electron-beam-sensitive materials.Cryogenic TEM(Cryo-TEM)has revolutionized structural biology,enabling the visualization of biomolecules in their near-native states at unprecedented detail.The low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum phenomena.Here,we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures,illustrating the electron beam-induced damage and the mitigating role of Cryo-TEM.This review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based materials.Furthermore,we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials,including the detection of charge order and novel topological spin textures.Finally,we discuss the future prospects of Cryo-TEM,emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030002)the National Key R&D Program of China(Grant No.2021YFA1400502)the National Natural Science Foundation of China(Grant Nos.52025023,and92163206)。
文摘Two-dimensional(2D)quantum materials have attracted extensive attention due to their superior properties at the atomic thickness.Numerous novel physical phenomena,including the quantum Hall effect,fractional quantum Hall effect,quantum anomalous Hall effect and topological superconductor phase or topological insulator phase,have been discovered on different2D quantum materials.Over the past decades,various technologies have been developed to prepare the 2D quantum materials and all of them have demonstrated their specific advantages.In this review,we comprehensively summarize the commonly used growth methods for the 2D quantum materials and discuss the corresponding controllable growth strategies.Finally,we provide a summary and a perspective for future studies.
文摘The search for and study of exotic quantum states in novel low-dimensional quantum materials have triggered extensive research in recent years. Here, we systematically study the electronic and magnetic structures in the newly discovered two-dimensional quantum material C3N within the framework of density functional theory. The calculations demonstrate that C3N is an indirect-band semiconductor with an energy gap of 0.38 eV, which is in good agreement with experimental observations. Inter- estingly, we find van Hove singularities located at energies near the Fermi level, which is half that of graphene. Thus, the Fermi energy easily approaches that of the singularities, driving the system to ferromagnetism, under charge carrier injection, such as electric field gating or hydrogen doping. These findings not only demonstrate that the emergence of magnetism stems from the itinerant electron mechanism rather than the effects of local magnetic impurities, but also open a new avenue to de- signing field-effect transistor devices for possible realization of an insulator-ferromagnet transition by tuning an external electric field.
基金support from the National Key R&D Program of China(Grants No.2021YFA1400202 and No.2021YFA1401800)National Natural Science Foundation of China(Grants No.11974243 and No.12141404)+1 种基金Natural Science Foundation of Shanghai(22ZR1479700)additional support from a Shanghai talent program.
文摘Upon femtosecond laser excitation in quantum materials,it is possible to study the many-body interactions through the non-equilibrium processes,realize ultrafast electronic phase transitions,and achieve photoinduced novel states or hidden states.Such studies of the interaction between the ultrafast laser and the quantum materials are the frontiers and attract significant research interests in the field of condensed matter physics.Time-and angle-resolved photoemission spectroscopy is a key experimental tool to study the ultrafast electronic dynamics in quantum materials after photoexcitation.This paper reviews the development of a high-resolution time-and angle-resolved photoemission system based on nonlinear optical crystals and the studies on the ultrafast electronic dynamics in quantum materials using such a setup,including(1)probing the unoccupied electronic states in quantum materials,(2)photoinduced ultrafast electronic phase transitions,and(3)photoinduced new states of matter.
基金City University of Hong Kong,Grant/Award Numbers:9380117,7005620,7020040。
文摘Interests in organic quantum materials(OQMs)have been explosively growing in the field of condensed physics of matter due to their rich chemistry and unique quantum properties.They are strongly correlated systems and show novel electromagnetic performance such as high-temperature superconducting,quantum sensing,spin electronics,quantum dots,topological insulating,quantum Hall effects,spin liquids,qubits,and so forth,which exhibit promising prospects in information communication and thus facilitate the construction of a modern intelligent society.This article reviews recent developments in the research on the electromagnetic characteristics of OQMs.We mainly give an overview on the progress of superconductors and quantum spin liquids based on organic materials and describe their possible mechanisms.Numerous experimental findings exhibit new exciton interactions and provide insights into exotic electronic properties.Finally,their association and strategies for realizing multiple quantum states in one system are discussed.
基金supported by the Beijing Municipal Natural Science Foundation(Grant No.Z180007)the National Natural Science Foundation of China(Grant Nos.11874003,11904015 and 52073006)the Australian Research Council(ARC)(LP180100722).
文摘In recent years,topological quantum materials(TQMs)have attracted intensive attention in the area of condensed matter physics due to their novel topologies and their promising applications in quantum computing,spin electronics and next-generation integrated circuits.Scanning tunneling microscopy/spectroscopy(STM/STS)is regarded as a powerful technique to characterize the local density of states with atomic resolution,which is ideally suited to the measurement of the bulk-boundary correspondence of TQMs.In this review,using STM/STS,we focus on recent research on bismuth-based TQMs,including quantum-spin Hall insulators,3D weak topological insulators(TIs),high-order TIs,topological Dirac semi-metals and dual TIs.Efficient methods for the modulation of the topological properties of the TQMs are introduced,such as interlayer interaction,thickness variation and local electric field perturbation.Finally,the challenges and prospects for this field of study are discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727902,12074372,12174385,12334014,and 12304112).
文摘Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.
基金the National Natural Science Foundation ofChina(No21176180)Research Fund for the Doctoral Program of Higher Education of China(No20100032110021) for the financial support
文摘Two novel organic hole-transporting materials have been synthesized by combination of triphenylamines（TPA） viaπ-conjugated bonds using Wittig reaction.The structures were characterized by NMR,FT-IR and HRMS.The optical,electrochemical and thermal properties of the materials were studied in detail.The results show that these two compounds have blue emission,proper HOMO levels and high thermal stability.Furthermore,a quantum chemical calculation on electron distribution of the two compounds was performed, which suggests the current synthesized materials would be promising candidates for hole-transporting materials.
基金supported by the National Natural Science Foundation of China(11222217)the State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics(MCMS-0414G01)
文摘Heat transport is a key energetic process in materials and devices. The reduced sample size, low dimension of the problem and the rich spectrum of material imperfections introduce fruitful phenomena at nanoscale. In this review, we summarize recent progresses in the understanding of heat transport process in low-dimensional materials, with focus on the roles of defects, disorder, interfaces, and the quantum- mechanical effect. New physics uncovered from computational simulations, experimental studies, and predictable models will be reviewed, followed by a perspective on open challenges.
基金supported by the National Natural Science Foundation of China (22175184 and 22105207)the Chinese Academy of Sciences (CAS) Project for Young Scientists in Basic Research (YSBR053)+1 种基金the Strategic Priority Research Programme of the Chinese Academy of Sciences (XDB0520202)the CAS Project for Young Scientists in Interdisciplinary Research。
文摘Due to the influence of quantum confinementeffect, two-dimensional (2D) materials like graphene exhibitunique and exceptional properties, highlighting the significance of low-dimensional materials in fundamental research and practical applications. This has led to highexpectations for one-dimensional (1D) atomic chain materialswith even lower dimensions. Compared with 2D materials,single 1D atomic chains reach their physical limits in bothdimensions, resulting in a more pronounced quantum confinement effect that gives rise to unexpected physical phenomena and will establish a new field for exploration. Herein,we review the emerging field concerning 1D van der Waals(vdW) atomic chains. We first summarize the various typesand structures of their bulk of the 1D vdW materials. Subsequently,we discuss the methods employed for their preparation and characterization. Finally, we analyze the challengesfaced during the development of 1D atomic chains and provide prospects for their future development.
基金financially supported by the National Key Research and Development Program of China (No. 2021YFA0718900)the National Natural Science Foundation of China (Nos.52073090 and 62074014)+1 种基金the Fundamental Research Funds for the Central Universities (No.FRF-TP-19-023A3Z)Beijing New-star Plan of Science and Technology (No. Z191100001119071)。
文摘The rare-earth nickelates(RENiO_(3)) exhibit an exceptional complex electronic phase diagram and multiple electronic phase transitions that enrich promising applications in correlated electronic devices beyond conventional semiconductors.Nevertheless,the practical applications of RENiO_(3) are challenged by their intrinsic thermodynamic metastability in material synthesis and high material cost.Therefore,developing an economical strategy to achieve the batch synthesis of RENiO_(3) is of vital importance.In this work,we enlarged the synthesis amount of RENiO_(3) up to 20 g per batch using chloride(KCI) assisted molten salt reaction.By optimizing the reaction conditions,the powder of RENiO_(3) with the cubic shape and average size of ~2μm was effectively synthesized,while their phase purity exceeded 95%.In addition,the cost to synthesize RENiO_(3) was further reduced by using rare-earth extraction intermediate products as the raw materials,instead of using the pure rare-earth precursors.It also achieved wide adjustments in the metal-to-insulator-transition temperature from160 to 420 K without significantly reducing the transition sharpness.By enlarging the synthesis amount and the reducing the cost,it paves the way to the device application of RENiO_(3).
基金supported by the National Key R&D Program of the MOST of China(No.2016YFA0300204)the National Natural Science Foundation of China(No.11227902)as part of the SiP·ME2 beamline project。
文摘Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has become particularly important.However,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation Facility.The beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 eV.In addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.
基金supported by the National Key Research and Development Program of China(2017YFA0207500)the National Natural Science Foundation of China(51973153)the Natural Science Foundation of Tianjin City(17JCJQJC44600)。
文摘Two-dimensional(2D)materials showcase great potentials in both fundamental research and technology development,thanks to their unique chemical and physical properties that are usually not available in corresponding bulk counterparts.As an emerging class of 2D materials,2D conductive metal-organic frameworks(2D c-MOFs)exhibit the characteristics of pre-designable and tunable structures,excellent crystallinity,intrinsic porosity and superior conductivity.During the past decade,2D c-MOFs have been rapidly developed in electronics,sensors,energy storage devices,etc.In this review,the electrical,magnetic and quantum properties of 2D c-MOFs are surveyed in detail.Their applications in semiconductor,metal,superconductor,topological insulator and porous magnet are highlighted.We envision that the combination of 2D c-MOFs with quantum materials could evoke rich physics,flexible chemistry and potential applications in both electronics and spintronics.
