Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-...Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.展开更多
Ising superconductivity, induced by the strong spin–orbit coupling(SOC) and inversion symmetry breaking, can lead to the in-plane upper critical field exceeding the Pauli limit and hold significant potential for adva...Ising superconductivity, induced by the strong spin–orbit coupling(SOC) and inversion symmetry breaking, can lead to the in-plane upper critical field exceeding the Pauli limit and hold significant potential for advancing the study of topological superconductivity. However, the enhancement of Ising superconductivity is still a challenging problem, important for engineering Majorana fermions and exploring topological quantum computing. In this study, we investigated the superconducting properties of a series of van der Waals NbSe_(2-x)Te_(x) nanosheets. The Ising superconductivity in NbSe_(2-x)Te_(x) nanosheets can be significantly enhanced by the substitution of Te, an element with strong SOC. The fitted in-plane upper critical field of Nb Se_(1.5)Te_(0.5) nanosheets at absolute zero temperature reaches up to 3.2 times the Pauli limit. Angular dependence of magnetoresistance measurements reveals a distinct two-fold rotational symmetry in the superconducting transition region, highlighting the role of strong SOC. In addition, the fitting results of the Berezinskii–Kosterlitz–Thouless(BKT) transition and the two-dimensional(2D) Tinkham formula provide strong evidence for 2D superconductivity. These findings offer new perspectives for the design and modulation of the Ising superconducting state and pave the way for their potential applications in topological superconductivity and quantum technologies.展开更多
Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields(B_(c2)). However, the requisite strong spin-orbital coupling in the Ising pai...Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields(B_(c2)). However, the requisite strong spin-orbital coupling in the Ising pairing mechanism generally renders these superconductors heavy-element dominant with notably low superconducting transition temperatures(Tc). Here, based on the Migdal-Eliashberg theory and the mean-field Bogoliubov-de Gennes Hamiltonian, we demonstrate a significant enhancement of Ising superconductivity in monolayer NbSe_(2) through surface fluorination, as evidenced by concomitant improvements in Tcand Bc_(2). This enhancement arises from three predominant factors. Firstly, fluorine atoms symmetrically and stably adhere to both sides of the monolayer NbSe_(2), thereby maintaining the out-of-plane mirror symmetry and locking carrier spins out-of-plane.Secondly, fluorination suppresses the charge density wave in monolayer NbSe_(2) and induces a van Hove singularity in the vicinity of the Fermi level, leading to a marked increase in the number of carriers and, consequently, strengthening the electron-phonon coupling(EPC). Lastly, the appearance of fluorine-related, low-frequency phonon modes further augments the EPC. Our findings suggest a promising avenue to elevate Tcin two-dimensional Ising superconductors without compromising their Ising pairing.展开更多
Understanding and control of many-body collective phenomena such as charge density wave(CDW)and superconductivity in atomically thin crystals remains a hot topic in material science.Here,using first-principles calcula...Understanding and control of many-body collective phenomena such as charge density wave(CDW)and superconductivity in atomically thin crystals remains a hot topic in material science.Here,using first-principles calculations,we find that 1T-HfTe_(2)possessing no CDWs in the bulk form,unexpectedly shows a stable 2×2 CDW order in the monolayer form,which can be attributed to the enhancement of electron–phonon coupling(EPC)in the monolayer.Meanwhile,the CDW induces a metal-to-insulator transition in monolayer 1T-HfTe_(2)through the accompanying lattice distortion.Remarkably,Ising superconductivity with a significantly enhanced in-plane critical field can emerge in centrosymmetric monolayer 1T-HfTe_(2)after the CDW is suppressed by electron doping.The Ising paring is revealed to be protected by the spin–orbital locking without the participation of the inversion symmetry breaking which is a must for conventional 2H-NbSe2-like Ising superconductors.Our results open a new window for designing and controlling novel quantum states in two-dimensional(2D)matter.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 12374196, 92165201, and 11634011)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800)+2 种基金the Chinese Academy of Sciences Project for Young Scientists in Basic Research (Grant No. YSBR-046)the Fundamental Research Funds for the Central Universities (Grant Nos. WK3510000006 and WK3430000003)Anhui Initiative in Quantum Information Technologies (Grant No. AHY170000)。
文摘Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62488201 and 1240041502)the China Postdoctoral Science Foundation (Grant No. 2024T170990)+2 种基金the National Key R&D Program of China (Grant No. 2022YFA1204100)the Chinese Academy of Sciences (Grant No. XDB33030100)the Innovation Program of Quantum Science and Technology (Grant No. 2021ZD0302700)。
文摘Ising superconductivity, induced by the strong spin–orbit coupling(SOC) and inversion symmetry breaking, can lead to the in-plane upper critical field exceeding the Pauli limit and hold significant potential for advancing the study of topological superconductivity. However, the enhancement of Ising superconductivity is still a challenging problem, important for engineering Majorana fermions and exploring topological quantum computing. In this study, we investigated the superconducting properties of a series of van der Waals NbSe_(2-x)Te_(x) nanosheets. The Ising superconductivity in NbSe_(2-x)Te_(x) nanosheets can be significantly enhanced by the substitution of Te, an element with strong SOC. The fitted in-plane upper critical field of Nb Se_(1.5)Te_(0.5) nanosheets at absolute zero temperature reaches up to 3.2 times the Pauli limit. Angular dependence of magnetoresistance measurements reveals a distinct two-fold rotational symmetry in the superconducting transition region, highlighting the role of strong SOC. In addition, the fitting results of the Berezinskii–Kosterlitz–Thouless(BKT) transition and the two-dimensional(2D) Tinkham formula provide strong evidence for 2D superconductivity. These findings offer new perspectives for the design and modulation of the Ising superconducting state and pave the way for their potential applications in topological superconductivity and quantum technologies.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12274013, 11874079)and the Independent Research Project of Medical Engineering Laboratory of Chinese PLA General Hospital (Grant No. 2022SYSZZKY10)+5 种基金Wujun Shi was supported by the Science and Technology Commission of Shanghai Municipality (STCSM) (Grant No. 22ZR1441800)Yong Xu and Wenhui Duan were supported by the Basic Science Center Project of NSFC (Grant No. 52388201)the National Natural Science Foundation of China (Grant No. 12334003)the National Science Fund for Distinguished Young Scholars (Grant No. 12025405)the Beijing Advanced Innovation Center for Future Chip (ICFC)the Beijing Advanced Innovation Center for Materials Genome Engineering。
文摘Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields(B_(c2)). However, the requisite strong spin-orbital coupling in the Ising pairing mechanism generally renders these superconductors heavy-element dominant with notably low superconducting transition temperatures(Tc). Here, based on the Migdal-Eliashberg theory and the mean-field Bogoliubov-de Gennes Hamiltonian, we demonstrate a significant enhancement of Ising superconductivity in monolayer NbSe_(2) through surface fluorination, as evidenced by concomitant improvements in Tcand Bc_(2). This enhancement arises from three predominant factors. Firstly, fluorine atoms symmetrically and stably adhere to both sides of the monolayer NbSe_(2), thereby maintaining the out-of-plane mirror symmetry and locking carrier spins out-of-plane.Secondly, fluorination suppresses the charge density wave in monolayer NbSe_(2) and induces a van Hove singularity in the vicinity of the Fermi level, leading to a marked increase in the number of carriers and, consequently, strengthening the electron-phonon coupling(EPC). Lastly, the appearance of fluorine-related, low-frequency phonon modes further augments the EPC. Our findings suggest a promising avenue to elevate Tcin two-dimensional Ising superconductors without compromising their Ising pairing.
基金supported by the National Natural Science Foundation of China(Nos.12274013 and 11874079)the open research fund program of the State key laboratory of low dimensional quantum physics(No.KF202103)the Independent Research Project of Medical Engineering Laboratory of Chinese PLA General Hospital(No.2022SYSZZKY10).
文摘Understanding and control of many-body collective phenomena such as charge density wave(CDW)and superconductivity in atomically thin crystals remains a hot topic in material science.Here,using first-principles calculations,we find that 1T-HfTe_(2)possessing no CDWs in the bulk form,unexpectedly shows a stable 2×2 CDW order in the monolayer form,which can be attributed to the enhancement of electron–phonon coupling(EPC)in the monolayer.Meanwhile,the CDW induces a metal-to-insulator transition in monolayer 1T-HfTe_(2)through the accompanying lattice distortion.Remarkably,Ising superconductivity with a significantly enhanced in-plane critical field can emerge in centrosymmetric monolayer 1T-HfTe_(2)after the CDW is suppressed by electron doping.The Ising paring is revealed to be protected by the spin–orbital locking without the participation of the inversion symmetry breaking which is a must for conventional 2H-NbSe2-like Ising superconductors.Our results open a new window for designing and controlling novel quantum states in two-dimensional(2D)matter.
