The newly discovered superconductivity in infinite-layer nickelate superconducting films has attracted much attention,largely because their crystalline and electronic structures are similar to those of high-T_(c) cupr...The newly discovered superconductivity in infinite-layer nickelate superconducting films has attracted much attention,largely because their crystalline and electronic structures are similar to those of high-T_(c) cuprate superconductors.The upper critical field can provide a great deal of information on the subject of superconductivity,but detailed experimental data are still lacking for these films.We present the temperature-and angle-dependence of resistivity,measured under different magnetic fields H in Nd_(0.8)Sr_(0.2)NiO_(2) thin films.The onset superconducting transition occurs at about 16.2 K at 0 T.Temperature-dependent upper critical fields,determined using a criterion very close to the onset transition,show a clear negative curvature near the critical transition temperature,which can be explained as a consequence of the paramagnetically limited effect on superconductivity.The temperaturedependent anisotropy of the upper critical field is obtained from resistivity data,which yields a value decreasing from 3 to 1.2 with a reduction in temperature.This can be explained in terms of the variable contribution from the orbital limit effect on the upper critical field.The angle-dependence of resistivity at a fixed temperature,and at different magnetic fields,cannot be scaled to a curve,which deviates from the prediction of the anisotropic Ginzburg-Landau theory.However,at low temperatures,the resistance difference can be scaled via the parameter H^(β)| cos θ|(β=6-1),with θ being the angle enclosed between the c-axis and the applied magnetic field.As the first detailed study of the upper critical field of nickelate thin films,our results clearly indicate a small anisotropy,and a paramagnetically limited effect,in terms of superconductivity,in nickelate superconductors.展开更多
Despite the recent discovery of superconductivity in Nd_(1-x)Sr_(x)NiO_(2) thin films,the absence of superconductivity and antiferromagnetism in their bulk materials remains a puzzle.Here we report the 1H NMR measurem...Despite the recent discovery of superconductivity in Nd_(1-x)Sr_(x)NiO_(2) thin films,the absence of superconductivity and antiferromagnetism in their bulk materials remains a puzzle.Here we report the 1H NMR measurements on powdered Nd0.85Sr0.15NiO2 samples by taking advantage of the enriched proton concentration after hydrogen annealing.We find a large full width at half maximum of the spectrum,which keeps increasing with decreasing the temperature T and exhibits an upturn behavior at low temperatures.The spin-lattice relaxation rate ^(1)T_(1)^(-1) is strongly enhanced when lowering the temperature,developing a broad peak at about 40 K,then decreases following a spin-wave-like behavior ^(1)T_(1)^(-1)∝T^(2) at lower temperatures.These results evidence a short-range glassy antiferromagnetic ordering of magnetic moments below 40 K and dominant antiferromagnetic fluctuations extending to much higher temperatures.Our findings reveal the strong electron correlations in bulk Nd_(0.85)Sr_(0.15)NiO_(2),and shed light on the mechanism of superconductivity observed in films of nickelates.展开更多
We report protonation in several compounds by an ionic-liquid-gating method, under optimized gating conditions.This leads to single superconducting phases for several compounds. Non-volatility of protons allows post-g...We report protonation in several compounds by an ionic-liquid-gating method, under optimized gating conditions.This leads to single superconducting phases for several compounds. Non-volatility of protons allows post-gating magnetization and transport measurements. The superconducting transition temperature Tc is enhanced to 43.5 K for FeSe0.93S0.07, and 41 K for Fe Se after protonation. Superconducting transitions with Tc^15 K for ZrNCl,~7.2 K for 1-TaS2, and ~3.8 K for Bi2Se3 are induced after protonation. Electric transport in protonated FeSe0.93S0.07 confirms high-temperature superconductivity. Our ^1H nuclear magnetic resonance(NMR)measurements on protonated Fe Se1-xSx reveal enhanced spin-lattice relaxation rate 1/^1T1 with increasing x,which is consistent with the LDA calculations that H+ is located in the interstitial sites close to the anions.展开更多
Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation re...Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.展开更多
Two-dimensional elec tronic spec troscopy(2DES)is a powerful met hod to probe the coherent electron dynamics in complicated systems.Stabilizing the phase difference of the incident ultrashort pulses is the mos t chall...Two-dimensional elec tronic spec troscopy(2DES)is a powerful met hod to probe the coherent electron dynamics in complicated systems.Stabilizing the phase difference of the incident ultrashort pulses is the mos t challenging par t for experimen tal demonstration of 2DES.Here,we present a tuto rial review on the 2DES proto cols based on active phase managements which are originally developed for quantum optics experiments.We introduce the 2DES techniques in box and pump-probe geometries with phase stabilization realized by interferometry,and outline the fully collinear 2DES approach with the frequency tagging by acoustic optical modulators and frequency combs.The combination of active phase managements,ultrashort pulses and other spectroscopic methods may open new opportunities to tackle essential challenges related to excited states.展开更多
We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.Th...We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.The NMR spectra at low fields are consistent with a zigzag magnetic order,indicating a large easy-axis anisotropy.With the field applied along the c*axis,the NMR spectra confirm the existence of a 1/3-magnetization plateau phase between 5.1 T and 7.1 T.The transition from the zigzag order to the 1/3-magnetization plateau phase is also found to be a first-order type.A monotonic decrease of the spin gap is revealed in the 1/3-magnetization plateau phase,which reaches zero at a quantum critical field H_(C)≈8.35 T before entering the fully polarized phase.These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions,hosting the possibility for Kitaev physics.Besides,well below the ordered phase,the 1/T_(1) at high fields shows either a level off or an enhancement upon cooling below 3 K,which suggests the existence of low-energy fluctuations.展开更多
The electronic properties of TiO2-terminated BaTiO3（001） surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward s...The electronic properties of TiO2-terminated BaTiO3（001） surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward shifted either at compressive or tension strains, while the inward shift of the Ba ions occurs only for high compressive strain, implying an enhanced electric dipole moment in the case of high compressive strain. In particular, an insulator–metal transition is predicted at a compressive biaxial strain of 0.0475. These changes present a very interesting possibility for engineering the electronic properties of ferroelectric BaTiO3（001） surface.展开更多
The M-series molecules with a ladder-typefused-ring core are promising acceptors (A) for organic solarcells (OSCs) owing to their excellent optoelectronic propertiesand facile synthesis. To further optimize their phot...The M-series molecules with a ladder-typefused-ring core are promising acceptors (A) for organic solarcells (OSCs) owing to their excellent optoelectronic propertiesand facile synthesis. To further optimize their photovoltaicperformance, two M-series acceptors (M36 and M13) with si-milar chemical structures are judiciously selected and com-bined in a photoactive layer to construct ternary OSCs. It isfound that a homogeneous mixed phase can be formed in theacceptor mixture due to the good compatibility between M36and M13, affording an enlarged exciton diffusion length that isconducive to efficient exciton dissociation. After blendingwith the polymer donor (D) PM6, the resultant ternary activelayer exhibits a more favorable phase-separated micro-structure and enhanced crystalline ordering than M36- andM13-based binary systems, thus enabling improved carriertransport and reduced charge recombination. Consequently,significant increases in both fill factor and photocurrent areachieved for the ternary device compared to the two binaryreference devices, delivering a high power conversion effi-ciency of 17.4%, which is among the highest efficiencies re-ported for A-D-A-type acceptors-based OSCs so far.展开更多
Carbon nitride(C_(3)N_(4))holds great promise for photocatalytic H_(2)O_(2)production from oxygen reduction.In spite of great research efforts,they still suffer from low catalytic efficiency primarily limited by the f...Carbon nitride(C_(3)N_(4))holds great promise for photocatalytic H_(2)O_(2)production from oxygen reduction.In spite of great research efforts,they still suffer from low catalytic efficiency primarily limited by the fast recombination of photogenerated charge carriers.In this work,we report the multiscale structural engineering of C_(3)N_(4)to significantly improve its optoelectronic properties and consequently photocatalytic performance.The product consists of porous spheres with high surface areas,abundant nitrogen defects,and alkali metal doping.Under visible light irradiation,our catalyst shows a remarkable H_(2)O_(2)production rate of 3,080μmol·g^(−1)·h^(−1),which is more than 10 times higher than that of bulk C_(3)N_(4)and exceeds those of most other C_(3)N_(4)-based photocatalysts.Moreover,the catalyst exhibits great stability,and can continuously work for 15 h without obvious activity decay under visible light irradiation,eventually giving rise to a high H_(2)O_(2)concentration of ca.45 mM.展开更多
The Kitaev model in a honeycomb lattice,which has an exactly solvable spin liquid as the ground state[1],has attracted a lot of research interests.Recently,Kitaev-type interactions were discovered in several quasi-2D,...The Kitaev model in a honeycomb lattice,which has an exactly solvable spin liquid as the ground state[1],has attracted a lot of research interests.Recently,Kitaev-type interactions were discovered in several quasi-2D,honeycomb lattice compounds,such as A2IrO3（A=Li,Na）[2-7]and α-RuCl3[8-15].In these compounds,both the spin-orbit coupling and electron correlations play an essential role in the emergent Mott insulator behaviors[2,16-19].展开更多
Guiding light and sound to propagate along desired paths is of fundamental significance in wave physics, with great application potential in diverse scenarios. The frontier fields of transformation optics (TO) and tra...Guiding light and sound to propagate along desired paths is of fundamental significance in wave physics, with great application potential in diverse scenarios. The frontier fields of transformation optics (TO) and transformation acoustics (TA) utilize coordinate transformations to manipulate the propagation trajectories of optical and acoustic waves with unprecedented precision and flexibility.展开更多
Chemical substitution during growth is a well-established method to manipulate electronic states of quantum materials, and leads to rich spectra of phase diagrams in cuprate and iron-based superconductors. Here we rep...Chemical substitution during growth is a well-established method to manipulate electronic states of quantum materials, and leads to rich spectra of phase diagrams in cuprate and iron-based superconductors. Here we report a novel and generic strategy to achieve nonvolatile electron doping in series of(i.e.11 and 122 structures) Fe-based superconductors by ionic liquid gating induced protonation at room temperature. Accumulation of protons in bulk compounds induces superconductivity in the parent compounds, and enhances the Tclargely in some superconducting ones. Furthermore, the existence of proton in the lattice enables the first proton nuclear magnetic resonance(NMR) study to probe directly superconductivity. Using Fe S as a model system, our NMR study reveals an emergent high-Tcphase with no coherence peak which is hard to measure by NMR with other isotopes. This novel electric-fieldinduced proton evolution opens up an avenue for manipulation of competing electronic states(e.g.Mott insulators), and may provide an innovative way for a broad perspective of NMR measurements with greatly enhanced detecting resolution.展开更多
Mesoscopic superconducting islands hosting Majorana zero modes(MZMs),or Majorana islands in short,offer a prototype of topological qubits.In this work we investigate theoretically the model of a generic Majorana islan...Mesoscopic superconducting islands hosting Majorana zero modes(MZMs),or Majorana islands in short,offer a prototype of topological qubits.In this work we investigate theoretically the model of a generic Majorana island tunneling-coupled to a singlepiece metallic substrate,hence an embedded Majorana island.We show the crucial consequences of an interplay between the topological ground states nonlocally addressed by the MZMs and the metallic bath with coherent electron propagation:on the one hand,the topological degeneracy on the Majorana island can be preserved,by virtue of the particle-hole symmetry,despite the apparent bath-induced coupling between MZMs;on the other hand,the electronic interference in the metallic bath may lead to profound alterations to the renormalization group behavior of the hybrid system towards low energy/temperature compared with conventional Kondo physics.This work serves to establish the model of embedded Majorana islands as an experimentally relevant and theoretically intriguing problem particularly in the direction of topological quantum computation.展开更多
The Majorana fermions/quasi-particles obey non-Abelian statistics and play an essential role in topological quantum computing.Theoretically,they can be realized as a zero-energy excitation in the vortex core of topolo...The Majorana fermions/quasi-particles obey non-Abelian statistics and play an essential role in topological quantum computing.Theoretically,they can be realized as a zero-energy excitation in the vortex core of topological superconductors,called Majorana zero mode(MZM).However,the coexisting low-energy bound states in vortex cores often bring difficulties for identifying MZM.In this review,we summarized recent STM studies on the vortex states of electron-doped FeSe-based superconductors such as(Li,Fe)OHFeSe and single-layer FeSe/SrTiO_(3).Zero-bias conductance peaks(ZBCP)are observed in the unpinned vortex cores of(Li,Fe)OHFeSe.It displays nearly quantized conductance and distinct spatial distributions with respect to nonzero bound states,which indicates their nontrivial origin.Meanwhile,single-layer FeSe/SrTiO_(3)film only has conventional Caroli-de Gennes-Matricon(CdGM)bound states without zero-energy mode,reflecting the characteristics of s-wave superconductor.These results not only provide strong evidence of MZM,but also shed light on its origin in FeSe-based superconductors.展开更多
基金the National Key R&D Program of China(Grant Nos.2016YFA0300401 and 2018YFA0704202)the National Natural Science Foundation of China(Grant Nos.12061131001,11774153,and 1861161004)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB25000000)the Fundamental Research Funds for the Central Universities(Grant No.0213-14380167)。
文摘The newly discovered superconductivity in infinite-layer nickelate superconducting films has attracted much attention,largely because their crystalline and electronic structures are similar to those of high-T_(c) cuprate superconductors.The upper critical field can provide a great deal of information on the subject of superconductivity,but detailed experimental data are still lacking for these films.We present the temperature-and angle-dependence of resistivity,measured under different magnetic fields H in Nd_(0.8)Sr_(0.2)NiO_(2) thin films.The onset superconducting transition occurs at about 16.2 K at 0 T.Temperature-dependent upper critical fields,determined using a criterion very close to the onset transition,show a clear negative curvature near the critical transition temperature,which can be explained as a consequence of the paramagnetically limited effect on superconductivity.The temperaturedependent anisotropy of the upper critical field is obtained from resistivity data,which yields a value decreasing from 3 to 1.2 with a reduction in temperature.This can be explained in terms of the variable contribution from the orbital limit effect on the upper critical field.The angle-dependence of resistivity at a fixed temperature,and at different magnetic fields,cannot be scaled to a curve,which deviates from the prediction of the anisotropic Ginzburg-Landau theory.However,at low temperatures,the resistance difference can be scaled via the parameter H^(β)| cos θ|(β=6-1),with θ being the angle enclosed between the c-axis and the applied magnetic field.As the first detailed study of the upper critical field of nickelate thin films,our results clearly indicate a small anisotropy,and a paramagnetically limited effect,in terms of superconductivity,in nickelate superconductors.
基金Supported by the National Natural Science Foundation of China(Grant Nos.51872328,11674392,11774401,and A0402/11927809)the National Key R&D Program of China(Grant Nos.2016YFA0300504 and 2016YFA0300401)+2 种基金China Postdoctoral Science Foundation(Grant No.2020M680797)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant Nos.18XNLG24,20XNLG19,and 21XNLG18)。
文摘Despite the recent discovery of superconductivity in Nd_(1-x)Sr_(x)NiO_(2) thin films,the absence of superconductivity and antiferromagnetism in their bulk materials remains a puzzle.Here we report the 1H NMR measurements on powdered Nd0.85Sr0.15NiO2 samples by taking advantage of the enriched proton concentration after hydrogen annealing.We find a large full width at half maximum of the spectrum,which keeps increasing with decreasing the temperature T and exhibits an upturn behavior at low temperatures.The spin-lattice relaxation rate ^(1)T_(1)^(-1) is strongly enhanced when lowering the temperature,developing a broad peak at about 40 K,then decreases following a spin-wave-like behavior ^(1)T_(1)^(-1)∝T^(2) at lower temperatures.These results evidence a short-range glassy antiferromagnetic ordering of magnetic moments below 40 K and dominant antiferromagnetic fluctuations extending to much higher temperatures.Our findings reveal the strong electron correlations in bulk Nd_(0.85)Sr_(0.15)NiO_(2),and shed light on the mechanism of superconductivity observed in films of nickelates.
基金supported by the National Natural Science Foundation of China under Grant Nos 51872328,11622437,11574394,11774423 and 11822412the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB30000000+5 种基金the Ministry of Science and Technology of China under Grant No 2016YFA0300504the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(RUC)(15XNLQ07,18XNLG14,19XNLG17)supported by the National Natural Science Foundation of China under Grant Nos 11774007 and U1832214supported by the Outstanding Innovative Talents Cultivation Funded Programs 2018 of Renmin University of Chinasupported by the U.S. Department of Energy,Office of Science,Basic Energy Sciences,Division of Materials Sciences and Engineering
文摘We report protonation in several compounds by an ionic-liquid-gating method, under optimized gating conditions.This leads to single superconducting phases for several compounds. Non-volatility of protons allows post-gating magnetization and transport measurements. The superconducting transition temperature Tc is enhanced to 43.5 K for FeSe0.93S0.07, and 41 K for Fe Se after protonation. Superconducting transitions with Tc^15 K for ZrNCl,~7.2 K for 1-TaS2, and ~3.8 K for Bi2Se3 are induced after protonation. Electric transport in protonated FeSe0.93S0.07 confirms high-temperature superconductivity. Our ^1H nuclear magnetic resonance(NMR)measurements on protonated Fe Se1-xSx reveal enhanced spin-lattice relaxation rate 1/^1T1 with increasing x,which is consistent with the LDA calculations that H+ is located in the interstitial sites close to the anions.
基金supported by the National Key R&D Program of China(No.2018YFA0209100 and No.2017YFA0303703)the National Natural Science Foundation of China(No.21922302,No.21873047,No.91850105,and No.91833305)+1 种基金the Fundamental Research Funds for the Central Universities(No.020414380126)Chun-feng Zhang acknowledges financial support from the Tang Scholar Program。
文摘Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.
基金This work is supported by the National Key R&D Program of China(No.2017YFA0303700 and No.2018YFA0209101)the National Natural Science Foundation of China(No.21922302,No.21873047,No.11904168,No.91833305,and No.91850105)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central University.
文摘Two-dimensional elec tronic spec troscopy(2DES)is a powerful met hod to probe the coherent electron dynamics in complicated systems.Stabilizing the phase difference of the incident ultrashort pulses is the mos t challenging par t for experimen tal demonstration of 2DES.Here,we present a tuto rial review on the 2DES proto cols based on active phase managements which are originally developed for quantum optics experiments.We introduce the 2DES techniques in box and pump-probe geometries with phase stabilization realized by interferometry,and outline the fully collinear 2DES approach with the frequency tagging by acoustic optical modulators and frequency combs.The combination of active phase managements,ultrashort pulses and other spectroscopic methods may open new opportunities to tackle essential challenges related to excited states.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2023YFA1406500, 2022YFA1402700, and 2021YFA1400400)the National Natural Science Foundation of China (Grant Nos. 12134020, 12374156, 12104503,12061131004, 12225407, and 12074174)。
文摘We perform ^(23)Na nuclear magnetic resonance(NMR) and magnetization measurements on an S=1,quasi-2D honeycomb lattice antiferromagnet Na_(3)Ni_(2)BiO_(6).A large positive Curie-Weiss constant of 22.9 K is observed.The NMR spectra at low fields are consistent with a zigzag magnetic order,indicating a large easy-axis anisotropy.With the field applied along the c*axis,the NMR spectra confirm the existence of a 1/3-magnetization plateau phase between 5.1 T and 7.1 T.The transition from the zigzag order to the 1/3-magnetization plateau phase is also found to be a first-order type.A monotonic decrease of the spin gap is revealed in the 1/3-magnetization plateau phase,which reaches zero at a quantum critical field H_(C)≈8.35 T before entering the fully polarized phase.These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions,hosting the possibility for Kitaev physics.Besides,well below the ordered phase,the 1/T_(1) at high fields shows either a level off or an enhancement upon cooling below 3 K,which suggests the existence of low-energy fluctuations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.1574091,51272078,and 51431006)the Natural Science Foundation of Guangdong Province of China(Grant No.2015A030313375)+1 种基金the Science and Technology Planning Project of Guangdong Province of China(Grant No.2015B090927006)the Program for International Innovation Cooperation Platform of Guangzhou City,China(Grant No.2014J4500016)
文摘The electronic properties of TiO2-terminated BaTiO3（001） surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward shifted either at compressive or tension strains, while the inward shift of the Ba ions occurs only for high compressive strain, implying an enhanced electric dipole moment in the case of high compressive strain. In particular, an insulator–metal transition is predicted at a compressive biaxial strain of 0.0475. These changes present a very interesting possibility for engineering the electronic properties of ferroelectric BaTiO3（001） surface.
基金supported by the National Natural Science Foundation of China (52130306)the National Key R&D Program of China (2022YFB4200303)+2 种基金the Fundamental Research Funds for the Central Universities (2024300413)the Program of Youth Innovation Promotion Association CAS (2021299)Guangdong Basic and Applied Basic Research Foundation (2023A1515110044)。
文摘The M-series molecules with a ladder-typefused-ring core are promising acceptors (A) for organic solarcells (OSCs) owing to their excellent optoelectronic propertiesand facile synthesis. To further optimize their photovoltaicperformance, two M-series acceptors (M36 and M13) with si-milar chemical structures are judiciously selected and com-bined in a photoactive layer to construct ternary OSCs. It isfound that a homogeneous mixed phase can be formed in theacceptor mixture due to the good compatibility between M36and M13, affording an enlarged exciton diffusion length that isconducive to efficient exciton dissociation. After blendingwith the polymer donor (D) PM6, the resultant ternary activelayer exhibits a more favorable phase-separated micro-structure and enhanced crystalline ordering than M36- andM13-based binary systems, thus enabling improved carriertransport and reduced charge recombination. Consequently,significant increases in both fill factor and photocurrent areachieved for the ternary device compared to the two binaryreference devices, delivering a high power conversion effi-ciency of 17.4%, which is among the highest efficiencies re-ported for A-D-A-type acceptors-based OSCs so far.
基金the financial support from the National Key R&D Program of China(No.2017YFA0204800)the National Natural Science Foundation of China(No.22002100)the Collaborative Innovation Center of Suzhou Nano Science and Technology,and the 111 Project and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices.
文摘Carbon nitride(C_(3)N_(4))holds great promise for photocatalytic H_(2)O_(2)production from oxygen reduction.In spite of great research efforts,they still suffer from low catalytic efficiency primarily limited by the fast recombination of photogenerated charge carriers.In this work,we report the multiscale structural engineering of C_(3)N_(4)to significantly improve its optoelectronic properties and consequently photocatalytic performance.The product consists of porous spheres with high surface areas,abundant nitrogen defects,and alkali metal doping.Under visible light irradiation,our catalyst shows a remarkable H_(2)O_(2)production rate of 3,080μmol·g^(−1)·h^(−1),which is more than 10 times higher than that of bulk C_(3)N_(4)and exceeds those of most other C_(3)N_(4)-based photocatalysts.Moreover,the catalyst exhibits great stability,and can continuously work for 15 h without obvious activity decay under visible light irradiation,eventually giving rise to a high H_(2)O_(2)concentration of ca.45 mM.
基金supported by the Ministry of Science and Technology of China(Grant No.2016YFA0300504)the National Natural Science Foundation of China(Grant No.11374364)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.14XNLF08)
文摘The Kitaev model in a honeycomb lattice,which has an exactly solvable spin liquid as the ground state[1],has attracted a lot of research interests.Recently,Kitaev-type interactions were discovered in several quasi-2D,honeycomb lattice compounds,such as A2IrO3（A=Li,Na）[2-7]and α-RuCl3[8-15].In these compounds,both the spin-orbit coupling and electron correlations play an essential role in the emergent Mott insulator behaviors[2,16-19].
文摘Guiding light and sound to propagate along desired paths is of fundamental significance in wave physics, with great application potential in diverse scenarios. The frontier fields of transformation optics (TO) and transformation acoustics (TA) utilize coordinate transformations to manipulate the propagation trajectories of optical and acoustic waves with unprecedented precision and flexibility.
基金supported by the Ministry of Science and Technology of China(2015CB921700,2016YFA0300504,2016YFA0301004,2016YFA0300401 and 2017YFA0302903)the National Natural Science Foundation of China(11374364,11522429,11374011 and 11534005)
文摘Chemical substitution during growth is a well-established method to manipulate electronic states of quantum materials, and leads to rich spectra of phase diagrams in cuprate and iron-based superconductors. Here we report a novel and generic strategy to achieve nonvolatile electron doping in series of(i.e.11 and 122 structures) Fe-based superconductors by ionic liquid gating induced protonation at room temperature. Accumulation of protons in bulk compounds induces superconductivity in the parent compounds, and enhances the Tclargely in some superconducting ones. Furthermore, the existence of proton in the lattice enables the first proton nuclear magnetic resonance(NMR) study to probe directly superconductivity. Using Fe S as a model system, our NMR study reveals an emergent high-Tcphase with no coherence peak which is hard to measure by NMR with other isotopes. This novel electric-fieldinduced proton evolution opens up an avenue for manipulation of competing electronic states(e.g.Mott insulators), and may provide an innovative way for a broad perspective of NMR measurements with greatly enhanced detecting resolution.
基金the support from the National Natural Science Foundation of China(Grant No.92265201)the support from the National Natural Science Foundation of China(Grant No.12247103)+2 种基金the support from the National Natural Science Foundation of China(Grant Nos.12322402,and 12274206)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302704)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.22JSZ005)。
文摘Mesoscopic superconducting islands hosting Majorana zero modes(MZMs),or Majorana islands in short,offer a prototype of topological qubits.In this work we investigate theoretically the model of a generic Majorana island tunneling-coupled to a singlepiece metallic substrate,hence an embedded Majorana island.We show the crucial consequences of an interplay between the topological ground states nonlocally addressed by the MZMs and the metallic bath with coherent electron propagation:on the one hand,the topological degeneracy on the Majorana island can be preserved,by virtue of the particle-hole symmetry,despite the apparent bath-induced coupling between MZMs;on the other hand,the electronic interference in the metallic bath may lead to profound alterations to the renormalization group behavior of the hybrid system towards low energy/temperature compared with conventional Kondo physics.This work serves to establish the model of embedded Majorana islands as an experimentally relevant and theoretically intriguing problem particularly in the direction of topological quantum computation.
基金supported by the Innovation Program for Quantum Science and Technology(Grant no.2021ZD0302800)National Natural Science Foundation of China(Grants Nos.92065202,11888101,11790312,11961160717,12225403,12104094)+2 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Science and Technology Commission of Shanghai Municipality,China(Grant Nos.19JC1412702,21TQ1400100)the China Postdoctoral Science Foundation(Grant Nos.BX20200097,2020M681137).
文摘The Majorana fermions/quasi-particles obey non-Abelian statistics and play an essential role in topological quantum computing.Theoretically,they can be realized as a zero-energy excitation in the vortex core of topological superconductors,called Majorana zero mode(MZM).However,the coexisting low-energy bound states in vortex cores often bring difficulties for identifying MZM.In this review,we summarized recent STM studies on the vortex states of electron-doped FeSe-based superconductors such as(Li,Fe)OHFeSe and single-layer FeSe/SrTiO_(3).Zero-bias conductance peaks(ZBCP)are observed in the unpinned vortex cores of(Li,Fe)OHFeSe.It displays nearly quantized conductance and distinct spatial distributions with respect to nonzero bound states,which indicates their nontrivial origin.Meanwhile,single-layer FeSe/SrTiO_(3)film only has conventional Caroli-de Gennes-Matricon(CdGM)bound states without zero-energy mode,reflecting the characteristics of s-wave superconductor.These results not only provide strong evidence of MZM,but also shed light on its origin in FeSe-based superconductors.
