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Evolution of Superconducting-Transition Temperature with Superfluid Density and Conductivity in Pressurized Cuprate Superconductors 被引量:1
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作者 赵金瑜 蔡树 +15 位作者 陈逸雯 顾根大 闫宏涛 郭静 韩金宇 王鹏玉 周亚洲 李延春 李晓东 任治安 吴奇 周兴江 丁阳 向涛 毛河光 孙力玲 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期110-117,共8页
What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law kn... What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense debate.Following the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal state.However,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure superconductors.In this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'law.We highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system. 展开更多
关键词 superconductorS TRANSITION CONDUCTIVITY
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Controversy Clouds Real Progress in Superconductor Research
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作者 Mark Peplow 《Engineering》 SCIE EI CAS CSCD 2024年第7期8-10,共3页
In the 8 March 2023 issue of the journal Nature,a paper attracted global attention with the report of a new superconductor material exhibiting ground-breaking properties[1,2].A group led by Ranga P.Dias,assistant prof... In the 8 March 2023 issue of the journal Nature,a paper attracted global attention with the report of a new superconductor material exhibiting ground-breaking properties[1,2].A group led by Ranga P.Dias,assistant professor of mechanical engineering at the University of Rochester(Rochester,NY,USA),described a hydride material that superconducted at around room temperature,albeit at pressures 10000 times greater than atmospheric pressure[3]. 展开更多
关键词 superconductor JOURNAL superconductor
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Strong Anisotropic Order Parameters at All-Nitride Ferromagnet/Superconductor Interfaces
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作者 Qiao Jin Meng Yang +16 位作者 Guozhu Song Nan Zhao Shengru Chen Haitao Hong Ting Cui Dongke Rong Qianying Wang Yiyan Fan Chen Ge Can Wang Jiachang Bi Yanwei Cao Liusuo Wu Shanmin Wang Kui-Juan Jin Zhi-Gang Cheng Er-Jia Guo 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第2期102-111,共10页
Proximity effects between superconductors and ferromagnets(SC/FM)hold paramount importance in comprehending the spin competition transpiring at their interfaces.This competition arises from the interplay between Coope... Proximity effects between superconductors and ferromagnets(SC/FM)hold paramount importance in comprehending the spin competition transpiring at their interfaces.This competition arises from the interplay between Cooper pairs and ferromagnetic exchange interactions.The proximity effects between transition metal nitrides(TMNs)are scarcely investigated due to the formidable challenges of fabricating high-quality SC/FM interfaces.We fabricated heterostructures comprising SC titanium nitride(TiN)and FM iron nitride(Fe_(3)N)with precise chemical compositions and atomically well-defined interfaces.The magnetoresistance of Fe_(3)N/TiN heterostructures shows a distinct magnetic anisotropy and strongly depends on the external perturbations.Moreover,the superconducting transition temperatureT_(C) and critical field of TiN experience notable suppression when proximity to Fe_(3)N.We observe the intriguing competition of interfacial spin orientations near𝑇T_(C)(∼1.25 K).These findings not only add a new materials system for investigating the interplay between superconductor and ferromagnets,but also potentially provide a building block for future research endeavors and applications in the realms of superconducting spintronic devices. 展开更多
关键词 PROXIMITY superconductor titanium
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Design of high-temperature superconductors at moderate pressures by alloying AlH3 or GaH3
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作者 Xiaowei Liang Xudong Wei +4 位作者 Eva Zurek Aitor Bergara Peifang Li Guoying Gao Yongjun Tian 《Matter and Radiation at Extremes》 SCIE EI CSCD 2024年第1期94-103,共10页
Since the discovery of hydride superconductors,a significant challenge has been to reduce the pressure required for their stabilization.In this context,we propose that alloying could be an effective strategy to achiev... Since the discovery of hydride superconductors,a significant challenge has been to reduce the pressure required for their stabilization.In this context,we propose that alloying could be an effective strategy to achieve this.We focus on a series of alloyed hydrides with the AMH_(6)composition,which can be made via alloying A15 AH_(3)(A=Al or Ga)with M(M=a group IIIB or IVB metal),and study their behavior under pressure.Seven of them are predicted to maintain the A15-type structure,similar to AH_(3)under pressure,providing a platform for studying the effects of alloying on the stability and superconductivity of AH_(3).Among these,the A15-type phases of AlZrH_(6)and AlHfH_(6)are found to be thermodynamically stable in the pressure ranges of 40–150 and 30–181 GPa,respectively.Furthermore,they remain dynamically stable at even lower pressures,as low as 13 GPa for AlZrH_(6)and 6 GPa for AlHfH_(6).These pressures are significantly lower than that required for stabilizing A15 AlH3.Additionally,the introduction of Zr or Hf increases the electronic density of states at the Fermi level compared with AlH3.This enhancement leads to higher critical temperatures(Tc)of 75 and 76 K for AlZrH_(6)and AlHfH_(6)at 20 and 10 GPa,respectively.In the case of GaMH_(6)alloys,where M represents Sc,Ti,Zr,or Hf,these metals reinforce the stability of the A15-type structure and reduce the lowest thermodynamically stable pressure for GaH_(3) from 160 GPa to 116,95,80,and 85 GPa,respectively.Particularly noteworthy are the A15-type GaMH_(6)alloys,which remain dynamically stable at low pressures of 97,28,5,and 6 GPa,simultaneously exhibiting high Tc of 88,39,70,and 49 K at 100,35,10,and 10 GPa,respectively.Overall,these findings enrich the family of A15-type superconductors and provide insights for the future exploration of high-temperature hydride superconductors that can be stabilized at lower pressures. 展开更多
关键词 ALLOYING ALLOYS superconductorS
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Two-fold symmetry of the in-plane resistance in kagome superconductor Cs(V_(1-x)Ta_(x))_(3)Sb_(5) with enhanced superconductivity
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作者 赵振 王汝文 +11 位作者 张宇航 祝轲 余维琪 韩烨超 刘家利 胡国静 郭辉 林晓 董晓莉 陈辉 杨海涛 高鸿钧 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期9-14,共6页
The kagome superconductor CsV_(3)Sb_(5) has attracted widespread attention due to its rich correlated electron states including superconductivity, charge density wave(CDW), nematicity, and pair density wave. Notably, ... The kagome superconductor CsV_(3)Sb_(5) has attracted widespread attention due to its rich correlated electron states including superconductivity, charge density wave(CDW), nematicity, and pair density wave. Notably, the modulation of the intertwined electronic orders by the chemical doping is significant to illuminate the cooperation/competition between multiple phases in kagome superconductors. In this study, we have synthesized a series of tantalum-substituted Cs(V_(1-x)Ta_(x))_(3)Sb_(5) by a modified self-flux method. Electrical transport measurements reveal that CDW is suppressed gradually and becomes undetectable as the doping content of x is over 0.07. Concurrently, the superconductivity is enhanced monotonically from T_(c) ~ 2.8 K at x = 0 to 5.2 K at x = 0.12. Intriguingly, in the absence of CDW, Cs(V_(1-x)Ta_(x))_(3)Sb_(5)(x = 0.12) crystals exhibit a pronounced two-fold symmetry of the in-plane angular-dependent magnetoresistance(AMR) in the superconducting state, indicating the anisotropic superconducting properties in the Cs(V_(1-x)Ta_(x))_(3)Sb_(5). Our findings demonstrate that Cs(V_(1-x)Ta_(x))_(3)Sb_(5) with the non-trivial band topology is an excellent platform to explore the superconductivity mechanism and intertwined electronic orders in quantum materials. 展开更多
关键词 kagome superconductor charge density wave rotation symmetry breaking
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Topological superconductors with spin-triplet pairings and Majorana Fermi arcs
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作者 黄石 罗熙 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期453-458,共6页
We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological insulator.By introducing inter-orbital spin-triplet pairing... We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological insulator.By introducing inter-orbital spin-triplet pairings term△3,there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface,similar to the case of Weyl semimetal.Furthermore,by adding an inversion-breaking term to the normal state,momentum-independent pairing terms with different parities can coexist in the Bd G Hamiltonian,which creates more Majorana modes similar to Andreev bound states and a richer phase diagram. 展开更多
关键词 topological surface states topological superconductors topological nodes Weyl points Majorana Fermi arcs
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Effect of the mixing of s-wave and chiral p-wave pairings on electrical shot noise properties of normal metal/superconductor tunnel junctions
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作者 胡雨辰 胡梁宾 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期538-545,共8页
We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion ... We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion symmetry. We investigate how the shot noise properties vary as the relative amplitude between the two parity components in the pairing potential is changed. It is demonstrated that some characteristics of the electrical shot noise properties of such tunnel junctions may depend sensitively on the relative amplitude between the two parity components in the pairing potential, and some significant changes may occur in the electrical shot noise properties when the relative amplitude between the two parity components is varied from the singlet s-wave pairing dominated regime to the chiral triplet p-wave pairing dominated regime. In the chiral triplet p-wave pairing dominated regime, the ratio of noise power to electric current is close to 2e both in the in-gap and in the out-gap region. In the singlet s-wave pairing dominated regime, the value of this ratio is close to 4e in the inner gap region but may reduce to about 2e in the outer gap region as the relative amplitude of the chiral triplet pairing component is increased. The variations of the differential shot noise with the bias voltage also exhibit some significantly different features in different regimes. Such different features can serve as useful diagnostic tools for the determination of the relative magnitude of the two parity components in the pairing potential. 展开更多
关键词 normal metal/superconductor tunnel junctions shot noise mixing of s-wave and chiral p-wave pairing spin–orbit coupling
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High Harmonic Spectroscopy Retrieves Electronic Structure of High-pressure Superconductors
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《Bulletin of the Chinese Academy of Sciences》 2024年第1期43-44,共2页
High pressure has revealed surprising physics and creates novel states in condensed matter.Exciting examples include near-roomtemperature superconductivity(T_(c)>200 K)in highlypressured hydrides such as H_(3)S and... High pressure has revealed surprising physics and creates novel states in condensed matter.Exciting examples include near-roomtemperature superconductivity(T_(c)>200 K)in highlypressured hydrides such as H_(3)S and LaH_(10). 展开更多
关键词 superconductor hydrides Structure
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Electronic Structure Investigation of 12442 Iron-Based Superconductors Based on Block-Layer Model
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作者 Jianan Bian Xinyuan Jiang +1 位作者 Yuchen Zou Yiming Yu 《材料科学与工程(中英文B版)》 2024年第1期21-26,共6页
Superconducting transition temperature(Tc),as a crucial parameter,exploring its relationship with various macroscopic and microscopic factors helps to understand the mechanism of high-temperature superconductivity fro... Superconducting transition temperature(Tc),as a crucial parameter,exploring its relationship with various macroscopic and microscopic factors helps to understand the mechanism of high-temperature superconductivity from multiple perspectives,aiding in a multidimensional comprehension of high-temperature superconductivity mechanisms.Drawing inspiration from the block-layer structure models of cuprate superconductors,we computationally investigated the interlayer interaction energies in the 12442-type iron-based superconducting materials AkCa_(2)Fe_(4)As_(4)F_(2)(Ak=K,Rb,Cs)systems based on the block-layer model and explored their relationship with Tc.We observed that an increase in interlayer combinative energy leads to a decrease in Tc,while conversely,a decrease in interlayer combination energy results in an increase in Tc.Further,we found that the contribution of the Fe 3d band structure,especially the 3dz2 orbital,to charge transfer is significant. 展开更多
关键词 Block-layer structural mode iron-based superconductor combinative energy superconducting transition temperature
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SOLIDIFIED PRODUCT FROM Bi-Sr-Ca-Cu-O MELT AND ITS TRANSFORMATION INTO SUPERCONDUCTOR
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作者 ZHANG Cheng HU Zhuangqi GE Yunlong WANG Yongzhong QIAO Guiwen Institute of Metal Research,Academia Sinica,Shenyang,China doctorate student Institute of Metal Research,Academia Sinica,Shenyang 110015,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1993年第6期383-390,共8页
The Bi_2(Sr,Ca)_3Cu_2O_x system superconductor was prepared by different melting procedures and after treatment.The effects of cooling rate,annealing temperature and time,as well as melting procedures on phase transfo... The Bi_2(Sr,Ca)_3Cu_2O_x system superconductor was prepared by different melting procedures and after treatment.The effects of cooling rate,annealing temperature and time,as well as melting procedures on phase transformation were investigated.The structure and properties were examined by X-ray diffraction,optical microscopy,EPMA,DTA,TGA and measurements of electric and magnetic properties.When the melt of nominal composition Bi_2(Sr,Ca)_3Cu_2O_x solidified in air,the Bi_2(Sr,Ca)_3Cu_2O_(8+δ)(2212)superconducting phase is stable,the easily solidified product including Bi_2(Sr,Ca)_2CuO_(6+δ)(2201)phase is metastable, and another may be amorphous if rapidly quenched.The last two may transform into 2212 phase by after treatment at an optimal annealing temperature ranging 780—870℃.While 2201 phase,prepared by the laser floating zone melting method,may easily transform into 2212 phase at layer or filament in shape which is favourable to improve the links among superconducting grains and critical current density. 展开更多
关键词 Bi system superconductor MELT stability phase transformation
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THE Bi-Sr-Ca-Cu-O BULK SUPERCONDUCTORS WITH RESISTANCE CLOSE TO ZERO ABOVE 110K
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作者 MAO Sining LIU Menglin +7 位作者 WU Zhenyi HUANG Hesheng GUO Zeng ZHAO Xin LIN Yaozhong HUANG Zhelin YU Jiali ZHANG Kongshi 《Chinese Physics Letters》 SCIE CAS 1988年第9期385-388,共4页
The bulk superconductors of the Bi-Sr-Ca-Cu-O system with resistance close to zero at the temperature above 110K have been prepared by solidstate reaction techniques.The onset of,transition is 125K.and the resistance ... The bulk superconductors of the Bi-Sr-Ca-Cu-O system with resistance close to zero at the temperature above 110K have been prepared by solidstate reaction techniques.The onset of,transition is 125K.and the resistance of the bulk samples has a sharp drop(~98%)near the Tc and is close to zero at 111K.Samples show a good stability.It has been implied that completely cutting off the"resistive tail"of this bulk superconductors should be possible. 展开更多
关键词 stability. RESISTANCE superconductorS
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The Superconducting Phases in Bi-Sr-Ca-Cu-O and Bi-Pb-Sr-Ca-Cu-O Superconductors at High Temperatures
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作者 He Qing Yu Dingan +2 位作者 Chang Shian Zhang Hong Sun Xu General Research Institute for Non-ferrous Metals,Beijing,100088,P.R.of China 《Rare Metals》 SCIE EI CAS CSCD 1989年第1期50-51,共2页
The addition Of Pb enhances the hightemperature stability as well as theproportion of the high Tphase in Bi-Sr-Ca-Cu-O superconductor.The sample A with nominal composi-tion of BiSrCaCuOwas synthesized bySolid state re... The addition Of Pb enhances the hightemperature stability as well as theproportion of the high Tphase in Bi-Sr-Ca-Cu-O superconductor.The sample A with nominal composi-tion of BiSrCaCuOwas synthesized bySolid state reaction.It was sintered in airat 1153K for 24h,followed by annealingat 773K for 24h and furnace-cooling.The sample B with a nominal compositionof BiPbSrCaCuOwas prepared bymixing PbO with the powder ofBiSrCaCuOwhich had been prefired at1113K for 24h,pressing,sintering at 展开更多
关键词 PB SR The Superconducting Phases in bi-sr-ca-cu-O and Bi-Pb-Sr-Ca-Cu-O superconductors at High Temperatures Cu Ca BI
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Customizing topological phases in the twisted bilayer superconductors with even-parity pairings
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作者 林丛豪 黄传帅 卢仙聪 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第8期1-5,共5页
We investigate the topological properties of twisted bilayer superconductors with different even-parity pairings in each layer.In the presence of spin-orbit coupling,the Hamiltonian is mapped into an effective odd-par... We investigate the topological properties of twisted bilayer superconductors with different even-parity pairings in each layer.In the presence of spin-orbit coupling,the Hamiltonian is mapped into an effective odd-parity superconductor.Based on this,we deduce the topological properties by examining the relative configuration between Fermi surface and Dirac pairing node.We show that mixed Rashba and Dresselhaus spin-orbit coupling and anisotropic hopping terms,which break the C_(4)symmetry of the Fermi surface,can induce first-order topological superconductors with non-zero bulk Chern number.This provides a versatile way to control the topological phases of bilayer superconductors by adjusting the twisted angle and chemical potential.We demonstrate our results using a typical twisted angle of 53.13°,at which the translation symmetry is restored and the Chern number and edge state are calculated using the Moir′e momentum. 展开更多
关键词 topological superconductors bilayer superconductors twistronics spin-orbit coupling
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Gate-Tunable Negative Differential Conductance in Hybrid Semiconductor–Superconductor Devices
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作者 刘明黎 潘东 +10 位作者 乐天 贺江波 贾仲谋 朱尚 杨光 吕昭征 刘广同 沈洁 赵建华 吕力 屈凡明 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第6期50-55,共6页
Negative differential conductance(NDC)serves as a crucial characteristic that reveals various underlying physics and transport process in hybrid superconducting devices.We report the observation of gate-tunable NDC ou... Negative differential conductance(NDC)serves as a crucial characteristic that reveals various underlying physics and transport process in hybrid superconducting devices.We report the observation of gate-tunable NDC outside the superconducting energy gap on two types of hybrid semiconductor–superconductor devices,i.e.,normal metal–superconducting nanowire–normal metal and normal metal–superconducting nanowire–superconductor devices.Specifically,we study the dependence of the NDCs on back-gate voltage and magnetic field.When the back-gate voltage decreases,these NDCs weaken and evolve into positive differential conductance dips;and meanwhile they move away from the superconducting gap towards high bias voltage,and disappear eventually.In addition,with the increase of magnetic field,the NDCs/dips follow the evolution of the superconducting gap,and disappear when the gap closes.We interpret these observations and reach a good agreement by combining the Blonder–Tinkham–Klapwijk(BTK)model and the critical supercurrent effect in the nanowire,which we call the BTK-supercurrent model.Our results provide an in-depth understanding of the tunneling transport in hybrid semiconductor–superconductor devices. 展开更多
关键词 superconductor TRANSPORT eventually
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Abnormal magnetoresistance effect in the Nb/Si superconductor–semiconductor heterojunction
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作者 胡志伟 邱祥冈 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期484-490,共7页
Ultrathin superconducting Nb films of about 8 nm thick have been deposited on heavily doped Si substrates through DC magnetron sputtering and then the high-quality Nb/Si superconductor–semiconductor heterojunctions h... Ultrathin superconducting Nb films of about 8 nm thick have been deposited on heavily doped Si substrates through DC magnetron sputtering and then the high-quality Nb/Si superconductor–semiconductor heterojunctions have been fabricated by electron beam lithography and reactive ion etching.An abnormal magnetoresistance effect,which manifests itself as a zero field resistance peak under a magnetic field applied perpendicular to the interface,has been distinctly observed when the Nb film is in the superconductiing state.By considering the heterojunction interface being equivalent to the structure of superconductor–barrier layer–superconductor configuration,we could generally understand this unusual effect based on the Andreev reflection mechanism.Our results can be of help for the future development on compatibility and scalability of the silicon-based nanoscale superconducting devices for integrated circuits and superconducting quantum electronics. 展开更多
关键词 superconductor MAGNETORESISTANCE HETEROJUNCTION
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Anisotropy of Electronic Spin Texture in the High-Temperature Cuprate Superconductor Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)
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作者 刘文晶 查鹤鸣 +3 位作者 顾根大 沈晓萍 叶茂 乔山 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第3期45-48,共4页
Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics.Here,by using spin-and angle-resolved photoemis... Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics.Here,by using spin-and angle-resolved photoemission spectroscopy,we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)and discover the anisotropy of spin polarizations at nodes alongΓ–X andΓ–Y directions.The breaking of C_(4)rotational symmetry in electronic spin texture may give deeper insights into understanding the ground state of cuprate superconductors. 展开更多
关键词 SYMMETRY superconductor BREAKING
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Majorana Corner Modes and Flat-Band Majorana Edge Modes in Superconductor/Topological-Insulator/Superconductor Junctions
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作者 陈晓婷 刘春晖 +1 位作者 许东辉 陈垂针 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第9期87-92,共6页
Recently,superconductors with higher-order topology have stimulated extensive attention and research interest.Higher-order topological superconductors exhibit unconventional bulk-boundary correspondence,thus allow exo... Recently,superconductors with higher-order topology have stimulated extensive attention and research interest.Higher-order topological superconductors exhibit unconventional bulk-boundary correspondence,thus allow exotic lower-dimensional boundary modes,such as Majorana corner and hinge modes.However,higher-order topological superconductivity has yet to be found in naturally occurring materials.We investigate higher-order topology in a two-dimensional Josephson junction comprised of two s-wave superconductors separated by a topological insulator thin film.We find that zero-energy Majorana corner modes,a boundary fingerprint of higherorder topological superconductivity,can be achieved by applying magnetic field.When an in-plane Zeeman field is applied to the system,two corner modes appear in the superconducting junction.Furthermore,we also discover a two-dimensional nodal superconducting phase which supports flat-band Majorana edge modes connecting the bulk nodes.Importantly,we demonstrate that zero-energy Majorana corner modes are stable when increasing the thickness of topological insulator thin film. 展开更多
关键词 field TOPOLOGICAL superconductorS
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Growth and Characterization of a New Superconductor GaBa2Ca3Cu4O11+δ
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作者 明学 何成平 +2 位作者 祝熙宇 缑慧阳 闻海虎 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第1期60-64,共5页
We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized sa... We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca0.85CuO2phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen.The obtained local chemical compositions revealed by energy dispersion x-ray spectroscopy are very close to the stoichiometric values. On some sub-millimeter crystal-like samples of the 1234 phase, we obtain a full Meissner shielding volume. From the temperature-dependent magnetizations, we determine the irreversibility fields and find that the system exhibits a highly anisotropic behavior. 展开更多
关键词 Cu4 PHASE superconductor
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Hole density dependent magnetic structure and anisotropy in Fe-pnictide superconductor
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作者 岳远放 黄忠兵 +2 位作者 黎欢 明星 郑晓军 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第9期463-467,共5页
The competition between different magnetic structures in hole-doped Fe-pnicitides is explored based on an extended five-orbital Hubbard model including long-range Coulomb interactions.Our results show that the stabili... The competition between different magnetic structures in hole-doped Fe-pnicitides is explored based on an extended five-orbital Hubbard model including long-range Coulomb interactions.Our results show that the stabilized magnetic structure evolves with increasing hole doping level.Namely,the stripe antiferromagnetic phase dominates at zero doping,while magnetic structures with more antiferromagnetic linking numbers such as the staggered tetramer,staggered trimer,and staggered dimer phases become energetically favorable as the hole density increases.At a certain doping level,energy degeneracy of different magnetic structures appears,indicating strong magnetic frustration and magnetic fluctuations in the system.We suggest that the magnetic competition induced by the hole doping may explain the fast decrease of the Neel temperature TNand the moderately suppressed magnetic moment in the hole doped Fe-pnicitides.Moreover,our results show a sign reversal of the kinetic energy anisotropy as the magnetic ground state evolves,which may be the mechanism behind the puzzling sign reversal of the in-plane resistivity anisotropy in hole-doped Fe-pnicitides. 展开更多
关键词 iron-pnictide superconductors magnetic structure resistivity anisotropy
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Ultralow-temperature heat transport study of noncentrosymmetric superconductor CaPtAs
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作者 万一民 程二建 +8 位作者 陈宇鑫 赵成成 涂成鹏 戴东喆 杨小帆 辛路 谢武 袁辉球 李世燕 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第12期158-161,共4页
The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity.Here,by employing ultralow-temperature thermal con... The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity.Here,by employing ultralow-temperature thermal conductivity measurement on CaPtAs single crystal,we study its superconducting gap structure.A negligible residual linear term of thermal conductivity(κ_(0)/T)in zero magnetic field and the field dependence ofκ_(0)/T indicate that CaPtAs has multiple superconducting gaps with a dominant s-wave component.This is consistent with recent nuclear quadrupole resonance measurements on CaPtAs.Our work puts a strong constraint on the theories to describe the superconducting pairing symmetry of CaPtAs. 展开更多
关键词 noncentrosymmetric superconductor thermal conductivity superconducting gap structure
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