In this paper, a strategy for the reactive power compensation and harmonic suppression of the power supply system in HT-7U superconductive Tokamak is proposed. The optimized approach is given in the parameters design...In this paper, a strategy for the reactive power compensation and harmonic suppression of the power supply system in HT-7U superconductive Tokamak is proposed. The optimized approach is given in the parameters design for passive filter. Also a controlling method with fast response time and good accuracy is put forward for the compensator, which is more suitable for the dynamic load.展开更多
By laser heated pedestal growth method, Bi_2Sr_2CaCu_2O_(8+δ) as-grown fibers with different morphologies were solidified in non-equilibrium condition at the rates of 0.1～14mm/min.At low rates,a(Sr_(1-x)Ca_x)CuO_2 p...By laser heated pedestal growth method, Bi_2Sr_2CaCu_2O_(8+δ) as-grown fibers with different morphologies were solidified in non-equilibrium condition at the rates of 0.1～14mm/min.At low rates,a(Sr_(1-x)Ca_x)CuO_2 phase with long and straight strips in shape and a white Cu-rich phase having a morphology of globular shape were found. With the increase of solidification rates,the phase (Sr_(1-x)Ca_x)CuO_2 becomes thinner and the Cu-rich phase becomes smaller and dispersive.When the solidification rates were last.another unstable phase(Sr_(1-x)Ca_x)Cu_2O_3 occurred.In fact,the tran- sition of the semiconductive as-grown fiber to the superconductor is a peritectoid reaction influenced by the annealing temperature and time.展开更多
Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure an...Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.展开更多
As one of the main materials in the practical application.of superconductor,lead(Pb)has been used to manufacture superconducting AC power cable,and some weak current fields.With the development of manufacturing,techno...As one of the main materials in the practical application.of superconductor,lead(Pb)has been used to manufacture superconducting AC power cable,and some weak current fields.With the development of manufacturing,technology,more and more researchers focus on exploring the physical and chemical properties of cryogenic superconducting materials,instead of blindly pursuing the improvement of the superconducting transition temperature(T_(c)).In this paper,the structural properties and superconducting transition temperature under high pressure of Pb have been studied by first-principles calculations.It has shown that Pb can withstand the compressive strain up to 10%while the lattice structure remains stable,indicated by the calculations of phonon band structures.From 0%to 10%compressive strain,there is neither a band-gap nor changing of the band structure.The.changing of electronic DOS.at the Fermi level leads to a decreasing of T_(c).Our calculations show that Pb is a stable elemental metallic superconductor even under high pressure,which explains the reason why it has been used in practical productions.展开更多
We investigate the controllable group velocity of a microwave probe field in a superconductive quantum circuit（SQC） pumped by microwave fields,and the use of such a SQC function as an artificial Λ-type three-level ...We investigate the controllable group velocity of a microwave probe field in a superconductive quantum circuit（SQC） pumped by microwave fields,and the use of such a SQC function as an artificial Λ-type three-level atom.The exchange between the subluminal and the superluminal states of the probe field can be realized simply by sweeping the pumping intensity,and the superluminal state is usually realized with a lower absorption.This work is one of the efforts to extend the study of electromagnetically induced transparency and its related properties from the lightwave band to the microwave band.展开更多
On the basis of the published literature and the interviews with some participants,this paper introduces the early history of the studies of superconductive materials and superconducting magnet during 1962～ 1966 in C...On the basis of the published literature and the interviews with some participants,this paper introduces the early history of the studies of superconductive materials and superconducting magnet during 1962～ 1966 in China,narrates the achievements of other relevant experimental and theoretical studies of superconductivity in that period briefly,and tries to give the authors' comments on that history.展开更多
The discovery of an extraordinarily superconductive large energy gap in SrTiO3 supported single-layer FeSe films has recently initiated a great deal of research interests in surface-enhanced superconductivity and supe...The discovery of an extraordinarily superconductive large energy gap in SrTiO3 supported single-layer FeSe films has recently initiated a great deal of research interests in surface-enhanced superconductivity and superconductive ultrathin films fabricated on crystal surfaces. On account of the instability of ultra-thin films in air, it is desirable to perform elec- trical transport measurement in ultra-high vaccum （UHV）. Here we review the experimental techniques of in situ electrical transport measurement and their applications on superconductive ultrathin films.展开更多
Laser heated pedestal growth technique (LHPG) has been used to fabricate BSCCO (BiSrCaCuO) superconductive wires.The critical current density of the wires has surpassed 5000A/cm^2 (78K, OT;cross area=1.04 mm^2).The fi...Laser heated pedestal growth technique (LHPG) has been used to fabricate BSCCO (BiSrCaCuO) superconductive wires.The critical current density of the wires has surpassed 5000A/cm^2 (78K, OT;cross area=1.04 mm^2).The fiber rods obtained directly from LHPG method are semiconductive and after heat treatment at temperature range from 780 to 870℃,they transformed into superconductive wires.Triple junctions and sharp grain boundary exist in the sample.HREM studies showed the intergrowth of (010) and (110),the occasional missing of CaCuO_2 layer in the 2212 phase.展开更多
Background The Nb/Cu film superconducting cavities offer several enhancements over traditional bulk niobium RF cavities,including improved mechanical and thermal stability,as well as a reduced sensitivity to DC magnet...Background The Nb/Cu film superconducting cavities offer several enhancements over traditional bulk niobium RF cavities,including improved mechanical and thermal stability,as well as a reduced sensitivity to DC magnetic fields.Despite these advantages,Nb/Cu film cavities produced via DC magnetron sputtering often exhibit a pronounced Q-slope issue,potentially due to the low-energy deposition process.In contrast,high-power impulse magnetron sputtering(HiPIMS)allows for greater peak power by employing a small duty cycle,to generate a higher ionization rates of target atoms,which,in turn,can control the deposition energy of the particles through the substrate bias voltage adjustments,thereby improving film quality.Methods Therefore,utilizing HiPIMS,we deposited Nb coatings on a 1.3 GHz dummy cavity and examined the impact of varying bias voltages on the films’crystal structure,microstructure,and superconductivity.Superior superconducting Nb coatings were achieved,as confirmed by X-ray diffractometry(XRD)for crystal structure,scanning electron microscopy(SEM)for surface and cross-section morphologies,four-probe measurement for low-temperature resistivity,and vibrating sample magnetometry(VSM)for superconducting properties.Results and Conclusion HiPIMS-deposited Nb coatings consistently displayed lattice constants approximating those of bulk Nb,tightly packed surface morphologies,and dense cross-sectional structures,with superconducting transition temperatures(Tc)reaching the theoretical value of 9.2 K.Notably,at a bias voltage of−100 V,the coatings in the cavity’s cell region transitioned from a polycrystalline to a single-crystalline structure,exhibiting increased density and enhanced surface continuity,with a predominance of the body-centered cubic(BCC)Nb(100)phase.These findings underscore the potential of HiPIMS in fabricating superconducting cavities with superior qualities.展开更多
High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary am...High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary ambient oxygen pressure be 2-3 orders lower than that in pulsed laser deposition (PLD).Tc0 is 85-87 K,and Jc～1.0×106 A/cm2.Atomic force microscopy (AFM) measurements show that no obvious particulates can be observed and the root mean square roughness is 7.8 nm.High stability DC superconducting quantum interference devices (DC-SQUID) was fabricated using this YBCO thin film.展开更多
Superconducting diodes,which enable dissipationless supercurrent flow in one direction while blocking it in the reverse direction,are emerging as pivotal components for superconducting electronics.The development of e...Superconducting diodes,which enable dissipationless supercurrent flow in one direction while blocking it in the reverse direction,are emerging as pivotal components for superconducting electronics.The development of editable superconducting diodes could unlock transformative applications,including dynamically reconfigurable quantum circuits that adapt to operational requirements.Here,we report the first observation of the superconducting diode effect(SDE)in LaAlO_(3)/KTaO_(3) heterostructures—a two-dimensional oxide interface superconductor with exceptional tunability.We observe a strong SDE in Hall-bar(or strip-shaped)devices under perpendicular magnetic fields(<15 Oe),with efficiencies above 40%and rectification signals exceeding 10 mV.Through conductive atomic force microscope lithography,we demonstrate reversible nanoscale editing of the SDE’s polarity and efficiency by locally modifying the superconducting channel edges.This approach enables multiple nonvolatile configurations within a single device,realizing an editable superconducting diode.Our work establishes LaAlO_(3)/KTaO_(3) as a platform for vortex-based nonreciprocal transport and provides a pathway toward designer quantum circuits with on-demand functionalities.展开更多
Motivated by the recent experimental discovery of superconductivity in rhombohedral tetralayer graphene,we investigate the pairing mechanism arising from the density–density interactions within the random-phase appro...Motivated by the recent experimental discovery of superconductivity in rhombohedral tetralayer graphene,we investigate the pairing mechanism arising from the density–density interactions within the random-phase approximation.This approach successfully highlights the dominance of the chiral p-wave pairing between electrons with the same spin and valley index at low densities,while also predicting the superconducting range in agreement with experimental findings.Furthermore,we examine the characteristics of distinct superconducting regions:SC1 and SC2 exhibit chiral finite-momentum superconductivity with pronounced phase fluctuations,whereas SC4 displays zero-momentum spin-singlet superconductivity.展开更多
Background In superconductive linear accelerator,the performance and stability can be impacted by gas adsorbed on cryogenic surfaces adversely.The cryogenic devices usually work at 4.2 K or 1.9 K and are refrigerated ...Background In superconductive linear accelerator,the performance and stability can be impacted by gas adsorbed on cryogenic surfaces adversely.The cryogenic devices usually work at 4.2 K or 1.9 K and are refrigerated by normal or super fluid liquid helium,respectively.Purpose The purpose of this paper is to study the character of gas migration in cryogenic tubes.Method Adsorption coefficient for hydrogen at 4.2 K is measured by experimental study.Then,a gas migration model is established based on the experimental results to depict the hydrogen migration process in cryogenic tubes.Results The experimental results and model analysis indicated that at cryogenic temperature(4.2 K),adsorption coefficient for hydrogen is very close to 1,which is several orders higher than the adsorption coefficient at room temperature,resulting in a unique pressure distribution pattern in cryogenic tubes when compared with the pressure distribution in room temperature tubes.Conclusions At 4.2 K or 1.9 K,the gas migration process is obviously different from the process at room temperature and is significantly affected by the gas adsorption on the cryogenic surfaces.The model established in this article can be applied not only to hydrogen migration in cryogenic tubes but also to other gas migration in tubes with high adsorption coefficient.展开更多
Superconducting elect rides have attracted growing attention for their potential to achieve high superconducting transition temperatures(T_(C))under pressure.However,many known elect rides are chemically reactive and ...Superconducting elect rides have attracted growing attention for their potential to achieve high superconducting transition temperatures(T_(C))under pressure.However,many known elect rides are chemically reactive and unstable,making high-quality single-crystal growth,characterization,and measurements difficult,and most do not exhibit superconductivity at ambient pressure.In contrast,La_(3) In stands out for its ambient-pressure superconductivity(T_(C)∼9.4 K)and the availability of high-quality single crystals.Here,we investigate its low-energy electronic structure using angle-resolved photoemission spectroscopy and first-principles calculations.The bands near the Fermi energy(E_(F))are mainly derived from La 5d and In 5p orbitals.A saddle point is directly observed at the Brillouin zone(BZ)boundary,while a three-dimensional Van Hove singularity crosses E_(F) at the BZ corner.First-principles calculations further reveal topological Dirac surface states within the bulk energy gap above E_(F).The coexistence of a high density of states and in-gap topological surface states near𝐸F suggests that La3In offers a promising platform for tuning superconductivity and exploring possible topological superconducting phases through doping or external pressure.展开更多
We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth o...We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth of ThMo_(2)Si_(2)C and ThRu_(2)Si_(2) units interconnected by equivalent Si-Si bonds that enhance inter-sublattice coupling.The refined lattice parameters are a=4.2212(1)Å and c=20.3899(7)Å.Electrical resistivity and magnetic susceptibility measurements of both polycrystalline and single-crystal samples consistently demonstrate bulk superconductivity with a transition temperature T_(c)∼6.0 K significantly higher than those of the constituent compound ThMo_(2)Si_(2)C and its related analogs.Under magnetic fields,the superconducting state exhibits a nearly isotropic behavior,which is attributed to strong covalent interlayer coupling.First-principles calculations reveal a substantial contribution from the Mo-d orbitals near the Fermi level,which exhibit several band-crossing points.The enhancement in T_(c) can be attributed to the synergistic combination of the valence electron concentration and the inter-sublattice self-doping effect between the[Ru_(2)Si_(2)]and[Mo_(2)Si_(2)C]layers.展开更多
High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-p...High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-principles calculations,we elucidate crucial corrections to the vibrational and superconducting properties arising from quantum and anharmonic ionic vibrations of SnH4 in P63/mmc phase at 150–240 GPa.Compared with the classical harmonic approximation,inclusion of these effects results in a pronounced softening(over 500 cm^(−1))of hydrogen-derived optical phonon modes,and increases the superconducting critical temperature(Tc)from 65 K to 79 K(μ^(*)=0.1;isotropic Migdal–Eliashberg theory),corresponding to a 22%enhancement.For μ^(*)=0.13,the predicted Tc is approximately 70 K.Analysis of the Eliashberg spectral function confirms that hydrogen vibrational modes constitute the dominant tuning mechanism.These results provide quantitative insights into quantum ionic effects in hydride superconductors.展开更多
We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconduc...We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconductor,correcting its long-standing classification as type-Ⅰ.Second,a complete set of anisotropic superconducting parameters is determined,including the critical fields,penetration depth and coherence length,which yield a Ginzburg–Landau parameterκ~1.5 and a moderate anisotropy ofγ~2.Our results indicate that this type-Ⅱsuperconductivity can be well-described by a conventional,weak-coupling,single-band s-wave pairing mechanism.This work fills a long-standing gap in the understanding of this archetypal superconductor.展开更多
A solenoid is typically used in normally conducting and superconducting radio frequency(SRF)photoinjectors to compensate for the projected transverse beam emittance.In the ELBE SRF Gun-Ⅱ,a superconducting solenoid is...A solenoid is typically used in normally conducting and superconducting radio frequency(SRF)photoinjectors to compensate for the projected transverse beam emittance.In the ELBE SRF Gun-Ⅱ,a superconducting solenoid is positioned inside the gun cryomodule approximately 0.7 m from the end of the gun cavity.The spherical aberration and multipole field effects caused by offset and tilt limit the reduction in beam emittance for high bunch charges.We designed a novel superconducting(SC)solenoid with a lower spherical aberration coefficient.In the simulation,the beam emittance from the spherical aberration decreased by 47%.Both the longitudinal and transverse fields were measured and analyzed using the formalism fitting method to assess the performance of the SC solenoid within the cryomodule and its influence on the beam transverse emittance.展开更多
We present a systematic investigation of the superconductivity in high-quality CsTi_(3)Bi_(5) single crystals by combining bulk property characterization and local-probe spectroscopy.Two successive superconducting tra...We present a systematic investigation of the superconductivity in high-quality CsTi_(3)Bi_(5) single crystals by combining bulk property characterization and local-probe spectroscopy.Two successive superconducting transitions are observed in this newly discovered kagome material.In the first stage,the diamagnetic response strengthens significantly from T_(c)~4.9 K to 4.6 K,followed by a broad transition below 4.6 K in the second stage.Moreover,different magnetic field dependences are observed for the two stages,where the first stage is field-insensitive while the second stage exhibits strong field dependence.The ultra-low magnetic field measurements indicate that the lower critical field H_(c1)(T)exhibits small anisotropy.Based on a comparative study of the superconducting state in CsBi2 and microscopic verification via scanning tunneling microscopy(STM),our results suggest the emergence of exotic and intrinsic superconductivity in this new titanium-based kagome superconductor,establishing it as a promising platform for further exploring the complexity of electronic states in the kagome lattice.展开更多
文摘In this paper, a strategy for the reactive power compensation and harmonic suppression of the power supply system in HT-7U superconductive Tokamak is proposed. The optimized approach is given in the parameters design for passive filter. Also a controlling method with fast response time and good accuracy is put forward for the compensator, which is more suitable for the dynamic load.
基金This work was supported by the National Natural Science Foundation of Chinathe National Laboratory of Rapidly Solidified Non-equilibrium Alloys,Institute of Metal Research,Academia Sinica
文摘By laser heated pedestal growth method, Bi_2Sr_2CaCu_2O_(8+δ) as-grown fibers with different morphologies were solidified in non-equilibrium condition at the rates of 0.1～14mm/min.At low rates,a(Sr_(1-x)Ca_x)CuO_2 phase with long and straight strips in shape and a white Cu-rich phase having a morphology of globular shape were found. With the increase of solidification rates,the phase (Sr_(1-x)Ca_x)CuO_2 becomes thinner and the Cu-rich phase becomes smaller and dispersive.When the solidification rates were last.another unstable phase(Sr_(1-x)Ca_x)Cu_2O_3 occurred.In fact,the tran- sition of the semiconductive as-grown fiber to the superconductor is a peritectoid reaction influenced by the annealing temperature and time.
文摘Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.
文摘As one of the main materials in the practical application.of superconductor,lead(Pb)has been used to manufacture superconducting AC power cable,and some weak current fields.With the development of manufacturing,technology,more and more researchers focus on exploring the physical and chemical properties of cryogenic superconducting materials,instead of blindly pursuing the improvement of the superconducting transition temperature(T_(c)).In this paper,the structural properties and superconducting transition temperature under high pressure of Pb have been studied by first-principles calculations.It has shown that Pb can withstand the compressive strain up to 10%while the lattice structure remains stable,indicated by the calculations of phonon band structures.From 0%to 10%compressive strain,there is neither a band-gap nor changing of the band structure.The.changing of electronic DOS.at the Fermi level leads to a decreasing of T_(c).Our calculations show that Pb is a stable elemental metallic superconductor even under high pressure,which explains the reason why it has been used in practical productions.
基金Project supported by the National Natural Science Foundation of China (Grant No. 111174040)the Fundamental Research Funds for the Central Universities
文摘We investigate the controllable group velocity of a microwave probe field in a superconductive quantum circuit（SQC） pumped by microwave fields,and the use of such a SQC function as an artificial Λ-type three-level atom.The exchange between the subluminal and the superluminal states of the probe field can be realized simply by sweeping the pumping intensity,and the superluminal state is usually realized with a lower absorption.This work is one of the efforts to extend the study of electromagnetically induced transparency and its related properties from the lightwave band to the microwave band.
文摘On the basis of the published literature and the interviews with some participants,this paper introduces the early history of the studies of superconductive materials and superconducting magnet during 1962～ 1966 in China,narrates the achievements of other relevant experimental and theoretical studies of superconductivity in that period briefly,and tries to give the authors' comments on that history.
基金supported by the National Basic Research Program of China(Grant Nos.2013CB921902 and 2011CB922200)the National Natural Science Foundation of China(Grant Nos.11227404,11274228,11521404,11174199,and 11134008)
文摘The discovery of an extraordinarily superconductive large energy gap in SrTiO3 supported single-layer FeSe films has recently initiated a great deal of research interests in surface-enhanced superconductivity and superconductive ultrathin films fabricated on crystal surfaces. On account of the instability of ultra-thin films in air, it is desirable to perform elec- trical transport measurement in ultra-high vaccum （UHV）. Here we review the experimental techniques of in situ electrical transport measurement and their applications on superconductive ultrathin films.
文摘Laser heated pedestal growth technique (LHPG) has been used to fabricate BSCCO (BiSrCaCuO) superconductive wires.The critical current density of the wires has surpassed 5000A/cm^2 (78K, OT;cross area=1.04 mm^2).The fiber rods obtained directly from LHPG method are semiconductive and after heat treatment at temperature range from 780 to 870℃,they transformed into superconductive wires.Triple junctions and sharp grain boundary exist in the sample.HREM studies showed the intergrowth of (010) and (110),the occasional missing of CaCuO_2 layer in the 2212 phase.
基金supported by High Energy Photon Source(HEPS),a major national science and technology infrastructure.
文摘Background The Nb/Cu film superconducting cavities offer several enhancements over traditional bulk niobium RF cavities,including improved mechanical and thermal stability,as well as a reduced sensitivity to DC magnetic fields.Despite these advantages,Nb/Cu film cavities produced via DC magnetron sputtering often exhibit a pronounced Q-slope issue,potentially due to the low-energy deposition process.In contrast,high-power impulse magnetron sputtering(HiPIMS)allows for greater peak power by employing a small duty cycle,to generate a higher ionization rates of target atoms,which,in turn,can control the deposition energy of the particles through the substrate bias voltage adjustments,thereby improving film quality.Methods Therefore,utilizing HiPIMS,we deposited Nb coatings on a 1.3 GHz dummy cavity and examined the impact of varying bias voltages on the films’crystal structure,microstructure,and superconductivity.Superior superconducting Nb coatings were achieved,as confirmed by X-ray diffractometry(XRD)for crystal structure,scanning electron microscopy(SEM)for surface and cross-section morphologies,four-probe measurement for low-temperature resistivity,and vibrating sample magnetometry(VSM)for superconducting properties.Results and Conclusion HiPIMS-deposited Nb coatings consistently displayed lattice constants approximating those of bulk Nb,tightly packed surface morphologies,and dense cross-sectional structures,with superconducting transition temperatures(Tc)reaching the theoretical value of 9.2 K.Notably,at a bias voltage of−100 V,the coatings in the cavity’s cell region transitioned from a polycrystalline to a single-crystalline structure,exhibiting increased density and enhanced surface continuity,with a predominance of the body-centered cubic(BCC)Nb(100)phase.These findings underscore the potential of HiPIMS in fabricating superconducting cavities with superior qualities.
基金This work was supported by the State Key Program of China (Grant No. G1998061412) the National 863 Project (Grant No. 863-CD070103) .
文摘High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary ambient oxygen pressure be 2-3 orders lower than that in pulsed laser deposition (PLD).Tc0 is 85-87 K,and Jc～1.0×106 A/cm2.Atomic force microscopy (AFM) measurements show that no obvious particulates can be observed and the root mean square roughness is 7.8 nm.High stability DC superconducting quantum interference devices (DC-SQUID) was fabricated using this YBCO thin film.
基金supported by the National Key R&D Program of China (Grant No.2023YFA1406400)the National Natural Science Foundation of China (Grant Nos.12534005 and 12325402)。
文摘Superconducting diodes,which enable dissipationless supercurrent flow in one direction while blocking it in the reverse direction,are emerging as pivotal components for superconducting electronics.The development of editable superconducting diodes could unlock transformative applications,including dynamically reconfigurable quantum circuits that adapt to operational requirements.Here,we report the first observation of the superconducting diode effect(SDE)in LaAlO_(3)/KTaO_(3) heterostructures—a two-dimensional oxide interface superconductor with exceptional tunability.We observe a strong SDE in Hall-bar(or strip-shaped)devices under perpendicular magnetic fields(<15 Oe),with efficiencies above 40%and rectification signals exceeding 10 mV.Through conductive atomic force microscope lithography,we demonstrate reversible nanoscale editing of the SDE’s polarity and efficiency by locally modifying the superconducting channel edges.This approach enables multiple nonvolatile configurations within a single device,realizing an editable superconducting diode.Our work establishes LaAlO_(3)/KTaO_(3) as a platform for vortex-based nonreciprocal transport and provides a pathway toward designer quantum circuits with on-demand functionalities.
基金supported by the National Natural Science Foundation of China (Grant Nos.12447125,12234016,and 12174317)the New Cornerstone Science Foundation。
文摘Motivated by the recent experimental discovery of superconductivity in rhombohedral tetralayer graphene,we investigate the pairing mechanism arising from the density–density interactions within the random-phase approximation.This approach successfully highlights the dominance of the chiral p-wave pairing between electrons with the same spin and valley index at low densities,while also predicting the superconducting range in agreement with experimental findings.Furthermore,we examine the characteristics of distinct superconducting regions:SC1 and SC2 exhibit chiral finite-momentum superconductivity with pronounced phase fluctuations,whereas SC4 displays zero-momentum spin-singlet superconductivity.
文摘Background In superconductive linear accelerator,the performance and stability can be impacted by gas adsorbed on cryogenic surfaces adversely.The cryogenic devices usually work at 4.2 K or 1.9 K and are refrigerated by normal or super fluid liquid helium,respectively.Purpose The purpose of this paper is to study the character of gas migration in cryogenic tubes.Method Adsorption coefficient for hydrogen at 4.2 K is measured by experimental study.Then,a gas migration model is established based on the experimental results to depict the hydrogen migration process in cryogenic tubes.Results The experimental results and model analysis indicated that at cryogenic temperature(4.2 K),adsorption coefficient for hydrogen is very close to 1,which is several orders higher than the adsorption coefficient at room temperature,resulting in a unique pressure distribution pattern in cryogenic tubes when compared with the pressure distribution in room temperature tubes.Conclusions At 4.2 K or 1.9 K,the gas migration process is obviously different from the process at room temperature and is significantly affected by the gas adsorption on the cryogenic surfaces.The model established in this article can be applied not only to hydrogen migration in cryogenic tubes but also to other gas migration in tubes with high adsorption coefficient.
基金supported by the National Natural Science Foundation of China(Grant Nos.12222413,12174443,12274459,and 12404266)the National Key R&D Program of China(Grant Nos.2023YFA1406500,2022YFA1403800,and 2022YFA1403103)+3 种基金the Natural Science Foundation of Shanghai (Grant No.23ZR1482200)the Natural Science Foundation of Ningbo (Grant No.2024J019)the Science Research Project of Hebei Education Department (Grant No.BJ2025060)the funding of Ningbo Yongjiang Talent Program。
文摘Superconducting elect rides have attracted growing attention for their potential to achieve high superconducting transition temperatures(T_(C))under pressure.However,many known elect rides are chemically reactive and unstable,making high-quality single-crystal growth,characterization,and measurements difficult,and most do not exhibit superconductivity at ambient pressure.In contrast,La_(3) In stands out for its ambient-pressure superconductivity(T_(C)∼9.4 K)and the availability of high-quality single crystals.Here,we investigate its low-energy electronic structure using angle-resolved photoemission spectroscopy and first-principles calculations.The bands near the Fermi energy(E_(F))are mainly derived from La 5d and In 5p orbitals.A saddle point is directly observed at the Brillouin zone(BZ)boundary,while a three-dimensional Van Hove singularity crosses E_(F) at the BZ corner.First-principles calculations further reveal topological Dirac surface states within the bulk energy gap above E_(F).The coexistence of a high density of states and in-gap topological surface states near𝐸F suggests that La3In offers a promising platform for tuning superconductivity and exploring possible topological superconducting phases through doping or external pressure.
基金supported by the National Key Research and Development Program of China (Grant Nos.2022YFA1403202 and 2023YFA1406101)the CAS Superconducting Research Project (Grant No.SCZX-0101)。
文摘We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th_(2)Mo_(2)Ru_(2)Si_(4)C,crystallized in a collapsed 22241-type structure.This structure is characterized by the intergrowth of ThMo_(2)Si_(2)C and ThRu_(2)Si_(2) units interconnected by equivalent Si-Si bonds that enhance inter-sublattice coupling.The refined lattice parameters are a=4.2212(1)Å and c=20.3899(7)Å.Electrical resistivity and magnetic susceptibility measurements of both polycrystalline and single-crystal samples consistently demonstrate bulk superconductivity with a transition temperature T_(c)∼6.0 K significantly higher than those of the constituent compound ThMo_(2)Si_(2)C and its related analogs.Under magnetic fields,the superconducting state exhibits a nearly isotropic behavior,which is attributed to strong covalent interlayer coupling.First-principles calculations reveal a substantial contribution from the Mo-d orbitals near the Fermi level,which exhibit several band-crossing points.The enhancement in T_(c) can be attributed to the synergistic combination of the valence electron concentration and the inter-sublattice self-doping effect between the[Ru_(2)Si_(2)]and[Mo_(2)Si_(2)C]layers.
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No.24JP126)the National Natural Science Foundation of China (Grant No.62174136)the Natural Science Basic Research Program of Shaanxi Province (Grant No.2025JC-YBMS-063)。
文摘High-pressure hydrides have emerged as promising superconducting materials,attracting considerable attention in recent years.In this work,by combining the stochastic self-consistent harmonic approximation with first-principles calculations,we elucidate crucial corrections to the vibrational and superconducting properties arising from quantum and anharmonic ionic vibrations of SnH4 in P63/mmc phase at 150–240 GPa.Compared with the classical harmonic approximation,inclusion of these effects results in a pronounced softening(over 500 cm^(−1))of hydrogen-derived optical phonon modes,and increases the superconducting critical temperature(Tc)from 65 K to 79 K(μ^(*)=0.1;isotropic Migdal–Eliashberg theory),corresponding to a 22%enhancement.For μ^(*)=0.13,the predicted Tc is approximately 70 K.Analysis of the Eliashberg spectral function confirms that hydrogen vibrational modes constitute the dominant tuning mechanism.These results provide quantitative insights into quantum ionic effects in hydride superconductors.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1611102,2022YFA1403903,2022YFA1602802,and 2023YFA1406101)the National Natural Science Foundation of China(Grant No.12304075)CAS Project for Young Scientists in Basic Research(Grant No.2022YSBR-048)。
文摘We report a comprehensive investigation of the superconducting properties of the mineral superconductor covellite(Cu S)using high-quality single crystals.First,we establish that Cu S is an intrinsic type-Ⅱsuperconductor,correcting its long-standing classification as type-Ⅰ.Second,a complete set of anisotropic superconducting parameters is determined,including the critical fields,penetration depth and coherence length,which yield a Ginzburg–Landau parameterκ~1.5 and a moderate anisotropy ofγ~2.Our results indicate that this type-Ⅱsuperconductivity can be well-described by a conventional,weak-coupling,single-band s-wave pairing mechanism.This work fills a long-standing gap in the understanding of this archetypal superconductor.
基金Open Access funding enabled and organized by Projekt DEAL.
文摘A solenoid is typically used in normally conducting and superconducting radio frequency(SRF)photoinjectors to compensate for the projected transverse beam emittance.In the ELBE SRF Gun-Ⅱ,a superconducting solenoid is positioned inside the gun cryomodule approximately 0.7 m from the end of the gun cavity.The spherical aberration and multipole field effects caused by offset and tilt limit the reduction in beam emittance for high bunch charges.We designed a novel superconducting(SC)solenoid with a lower spherical aberration coefficient.In the simulation,the beam emittance from the spherical aberration decreased by 47%.Both the longitudinal and transverse fields were measured and analyzed using the formalism fitting method to assess the performance of the SC solenoid within the cryomodule and its influence on the beam transverse emittance.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1611102,2022YFA1403903,2023YFA1406101,and 2022YFA1204100)the National Natural Science Foundation of China(Grant Nos.12304075 and 62488201)+1 种基金CAS Project for Young Scientists in Basic Research(Grant Nos.2022YSBR-048 and YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘We present a systematic investigation of the superconductivity in high-quality CsTi_(3)Bi_(5) single crystals by combining bulk property characterization and local-probe spectroscopy.Two successive superconducting transitions are observed in this newly discovered kagome material.In the first stage,the diamagnetic response strengthens significantly from T_(c)~4.9 K to 4.6 K,followed by a broad transition below 4.6 K in the second stage.Moreover,different magnetic field dependences are observed for the two stages,where the first stage is field-insensitive while the second stage exhibits strong field dependence.The ultra-low magnetic field measurements indicate that the lower critical field H_(c1)(T)exhibits small anisotropy.Based on a comparative study of the superconducting state in CsBi2 and microscopic verification via scanning tunneling microscopy(STM),our results suggest the emergence of exotic and intrinsic superconductivity in this new titanium-based kagome superconductor,establishing it as a promising platform for further exploring the complexity of electronic states in the kagome lattice.
