We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band...We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips’ ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials.展开更多
Topological materials, hosting topological nontrivial electronic band, have attracted widespread attentions. As an application of topology in physics, the discovery and study of topological materials not only enrich t...Topological materials, hosting topological nontrivial electronic band, have attracted widespread attentions. As an application of topology in physics, the discovery and study of topological materials not only enrich the existing theoretical framework of physics, but also provide fertile ground for investigations on low energy excitations, such as Weyl fermions and Majorana fermions, which have not been observed yet as fundamental particles. These quasiparticles with exotic physical properties make topological materials the cutting edge of scientific research and a new favorite of high tech. As a typical example, Majorana fermions, predicted to exist in the edge state of topological superconductors, are proposed to implement topological error-tolerant quantum computers. Thus, the detection of topological superconductivity has become a frontier in condensed matter physics and materials science. Here, we review a way to detect topological superconductivity triggered by the hard point contact: tip-induced superconductivity(TISC) and tip-enhanced superconductivity(TESC). The TISC refers to the superconductivity induced by a non-superconducting tip at the point contact on non-superconducting materials. We take the elaboration of the chief experimental achievement of TISC in topological Dirac semimetal Cd_3As_2 and Weyl semimetal Ta As as key components of this article for detecting topological superconductivity. Moreover, we also briefly introduce the main results of another exotic effect, TESC, in superconducting Au_2Pb and Sr_2RuO_4 single crystals, which are respectively proposed as the candidates of helical topological superconductor and chiral topological superconductor. Related results and the potential mechanism are conducive to improving the comprehension of how to induce and enhance the topological superconductivity.展开更多
The origin of superconductivity observed at the point contact between the normal metal tip and the topological material remains uncertain due to the potential presence of superconducting elements or allotropes impurit...The origin of superconductivity observed at the point contact between the normal metal tip and the topological material remains uncertain due to the potential presence of superconducting elements or allotropes impurities.It is imperative to seek out a topological material entirely free of superconducting impurities and induce superconductivity between it and normal tips to verify the source of the induced superconductivity.Here,we report the observation of superconductivity up to 9 K induced at point contacts between normal metal tips and the topological material grey arsenic,which is free of superconductivity.The determined temperature dependencies of superconducting gapsΔ(T)deviate from the Bardeen-Cooper-Schriefer(BCS)superconductivity law,exhibiting abnormal behavior.Furthermore,the highly anisotropic upper critical field H_(c2)(T)suggests the anisotropy of the projected interfacial Fermi surface.By tuning the junction resistance,we obtained a negative correlation between the superconducting gapΔand the efective barrier height Z,which validates the interfacial coupling strength as a key factor in the observed tip-induced superconductivity.These experimental results provide guidance for the relevant theory about tip-induced superconductivity on topological materials.展开更多
The metallic tip-induced superconductivity in normal Weyl semimetal offers a promising platform to study topological superconductivity,which is currently a research focus in condensed matter physics.Here we experiment...The metallic tip-induced superconductivity in normal Weyl semimetal offers a promising platform to study topological superconductivity,which is currently a research focus in condensed matter physics.Here we experimentally uncover that unconventional superconductivity can be induced by hard point contact(PC)method of ferromagnetic tips in Ta As single crystals.The magneto-transport measurements of the ferromagnetic tip-induced superconducting(FTISC)states exhibit the quantum oscillations,which reveal that the superconductivity is induced in the topologically nontrivial Fermi surface of the Weyl semimetal,and show compatibility of ferromagnetism and induced superconductivity.We further measure the point contact spectra(PCS)of tunneling transport for FTISC states which are potentially of nontrivial topology.Considering that the magnetic Weyl semimetal with novel superconductivity is hard to realize in experiment,our results show a new route to investigate the unconventional superconductivity by combining the topological semimetal with ferromagnetism through hard PC method.展开更多
基金Project supported by the National Key R&D Program of China(Grant Nos.2017YFA0302904,2017YFA0303201,2018YFA0305602,and 2016YFA0300604)the National Natural Science Foundation of China(Grants Nos.12074002,11574372,11674331,11804379,and 11874417)+4 种基金the National Basic Research Program of China(Grant No.2015CB921303)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grants Nos.XDB07020300,XDB07020100,and XDB33030100)the Collaborative Innovation Program of Hefei Science Center,the Chinese Academy of Sciences(Grant No.2020HSCCIP002)CASHIPS Director’s Fund,China(Grant No.BJPY2019B03)the Recruitment Program for Leading Talent Team of Anhui Province,China(2019-16)。
文摘We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips’ ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials.
基金financially supported by the National Program on Key Basic Research Project(2018YFA0305604 and 2017YFA0303302)National Natural Science Foundation of China(11774008,381/0401210001)+2 种基金the Key Research Program of the Chinese Academy of Sciences(XDPB08-2)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics,Tsinghua University(KF201703)China Postdoctoral Science Foundation(130/0401130005)
文摘Topological materials, hosting topological nontrivial electronic band, have attracted widespread attentions. As an application of topology in physics, the discovery and study of topological materials not only enrich the existing theoretical framework of physics, but also provide fertile ground for investigations on low energy excitations, such as Weyl fermions and Majorana fermions, which have not been observed yet as fundamental particles. These quasiparticles with exotic physical properties make topological materials the cutting edge of scientific research and a new favorite of high tech. As a typical example, Majorana fermions, predicted to exist in the edge state of topological superconductors, are proposed to implement topological error-tolerant quantum computers. Thus, the detection of topological superconductivity has become a frontier in condensed matter physics and materials science. Here, we review a way to detect topological superconductivity triggered by the hard point contact: tip-induced superconductivity(TISC) and tip-enhanced superconductivity(TESC). The TISC refers to the superconductivity induced by a non-superconducting tip at the point contact on non-superconducting materials. We take the elaboration of the chief experimental achievement of TISC in topological Dirac semimetal Cd_3As_2 and Weyl semimetal Ta As as key components of this article for detecting topological superconductivity. Moreover, we also briefly introduce the main results of another exotic effect, TESC, in superconducting Au_2Pb and Sr_2RuO_4 single crystals, which are respectively proposed as the candidates of helical topological superconductor and chiral topological superconductor. Related results and the potential mechanism are conducive to improving the comprehension of how to induce and enhance the topological superconductivity.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1403203,2017YFA0302904,2017YFA0303201,2018YFA0305602,and 2016YFA0300604)the National Natural Science Foundation of China(Grant Nos.12074002,11574372,11674331,11804379,11874417,and 92265104)+4 种基金the National Basic Research Program of China(Grant No.2015CB921303)the“Strategic Priority Research Program(B)”of the Chinese Academy of Sciences(Grant Nos.XDB07020300,XDB07020100,and XDB33030100)the Recruitment Program for Leading Talent Team of Anhui Province(2019-16)the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)supported by the High Magnetic Field Laboratory of Anhui Province,China。
文摘The origin of superconductivity observed at the point contact between the normal metal tip and the topological material remains uncertain due to the potential presence of superconducting elements or allotropes impurities.It is imperative to seek out a topological material entirely free of superconducting impurities and induce superconductivity between it and normal tips to verify the source of the induced superconductivity.Here,we report the observation of superconductivity up to 9 K induced at point contacts between normal metal tips and the topological material grey arsenic,which is free of superconductivity.The determined temperature dependencies of superconducting gapsΔ(T)deviate from the Bardeen-Cooper-Schriefer(BCS)superconductivity law,exhibiting abnormal behavior.Furthermore,the highly anisotropic upper critical field H_(c2)(T)suggests the anisotropy of the projected interfacial Fermi surface.By tuning the junction resistance,we obtained a negative correlation between the superconducting gapΔand the efective barrier height Z,which validates the interfacial coupling strength as a key factor in the observed tip-induced superconductivity.These experimental results provide guidance for the relevant theory about tip-induced superconductivity on topological materials.
基金financially supported by the National Key R&D Program of China (2018YFA0305604, 2017YFA0303302, and 2016YFA0301604)the National Natural Science Foundation of China (11888101, 11774008, 0401210001, 11574008, 11761161003, 11825401, 11704279, 11774255, U1832214, and 11774007)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB28000000)the Beijing Natural Science Foundation (Z180010)the Key Project of Natural Science Foundation of Tianjin City (17JCZDJC30100)China Postdoctoral Science Foundation (0401130005)
文摘The metallic tip-induced superconductivity in normal Weyl semimetal offers a promising platform to study topological superconductivity,which is currently a research focus in condensed matter physics.Here we experimentally uncover that unconventional superconductivity can be induced by hard point contact(PC)method of ferromagnetic tips in Ta As single crystals.The magneto-transport measurements of the ferromagnetic tip-induced superconducting(FTISC)states exhibit the quantum oscillations,which reveal that the superconductivity is induced in the topologically nontrivial Fermi surface of the Weyl semimetal,and show compatibility of ferromagnetism and induced superconductivity.We further measure the point contact spectra(PCS)of tunneling transport for FTISC states which are potentially of nontrivial topology.Considering that the magnetic Weyl semimetal with novel superconductivity is hard to realize in experiment,our results show a new route to investigate the unconventional superconductivity by combining the topological semimetal with ferromagnetism through hard PC method.