Low-Dimensional Transport Research Unit

Principal Investigator

PI Name Ding Zhang
Degree Ph.D.
Title Unit Leader
Brief Resume
2014 PhD in physics, Max Planck Institute for Solid State Research, Stuttgart, Germany
2014 PhD in physics, University of Stuttgart, Stuttgart, Germany
2014 Post-doctor, Tsinghua University, Beijing, China
2016 Assistant Professor, Tsinghua University, Beijing, China
2018 Associate Professor, Tsinghua University, Beijing, China (-present)
2021 Unit Leader, Low-Dimensional Transport Research Unit, Cross-Divisional Materials Research Program, RIKEN Center for Emergent Matter Science (-present)

Outline

Our research unit studies a variety of low-dimensional electronic systems that undergo Cooper pairing. We aim at addressing some of the basic properties such as the pairing mechanism and the pairing symmetry. Furthermore, we look for novel quantum phenomena in reduced dimensions under specially designed conditions. The experimental knobs include stacking van der Waals heterostructures, injecting lithium/hydrogen ions, varying the magnetic field orientations at ultralow temperatures, and ramping up the magnetic field to an extremely high value. By collaborating closely with experimental and theoretical experts in the field, we hope to gain a comprehensive understanding of those exotic phenomena.

Research Fields

Physics

Keywords

Condensed matter physics
High-temperature superconductor
Josephson effect
Low dimensional superconductors
Van der Waals epitaxy

Results

Type-II Ising pairing in few-layer stanene

In recent years, two-dimensional non-centrosymmetric superconductors show large in-plane upper critical fields, far exceeding the conventionally expected value. To explain this phenomenon, a so-called Ising pairing mechanism was proposed, in which the paired electrons stem from spin-split bands with the spin orientationslocked out-of-plane. Recently, we observed enhanced in-plane upper critical fieldin a highly symmetric material—few-layer stanene. This is based on our previous discovery of superconductivity in the same material. In the more recent work, we clearly observed an up-turn behavior of the critical magnetic field as the temperature approaches absolute zero. However, since stanene is centrosymmetric, the observed behaviors cannot be explained by the established theory of Ising superconductivity. We therefore proposed a new type of Ising pairing—type-II Ising paring—which results from the combination of spin-orbit coupling and high lattice symmetry of the materials. Ourwork provides strong evidence for the existence of Ising superconductivityand substantially broadens the scope for the realization of Ising superconductors.

 

Figure

Illustration of the stanene lattice with Ising-like Cooper pairs. The background shows the corresponding band structure. Upper right shows the element information of Sn.

Members

Ding Zhang

Unit Leader ding.zhang[at]riken.jp

Publications

  1. D. Zhang, J. Falson, S. Schmult, W. Dietsche, and J. H. Smet

    Quasiparticle Tunneling across an Exciton Condensate

    Phys. Rev. Lett. 124, 246801 (2020)
  2. J. Falson, Y. Xu, M. Liao, Y. Zang, K. Zhu, C. Wang, Z. Zhang, H. Liu, W. Duan, K. He, H. Liu, J. H. Smet, D. Zhang, and Q.-K. Xue

    Type-II Ising pairing in few-layer stanene

    Science 367, 1454 (2020)
  3. M. Rafique, Z. Feng, Z. Lin, X. Wei, M. Liao, D. Zhang, K. Jin, and Q. Xue

    Ionic Liquid Gating Induced Protonation of Electron-Doped Cuprate Superconductors

    Nano Lett. 19, 7775–7780 (2019)
  4. M. Liao, Y. Zhu, J. Zhang, R. Zhong, J. Schneeloch, G. Gu, K. Jiang, D. Zhang, X. Ma, and Q. Xue

    Superconductor–Insulator Transitions in Exfoliated Bi2Sr2CaCu2O8+δFlakes

    Nano Lett. 18, 5660–5665 (2018)
  5. M. Liao, Y. Zang, Z. Guan, H. Li, Y. Gong, K. Zhu, X.-P. Hu, D. Zhang, Y. Xu, Y.-Y. Wang, K. He, X.-C. Ma, S.-C. Zhang, and Q.-K. Xue

    Superconductivity in few-layer stanene

    Nat. Phys. 14, 344 (2018)

お問い合わせ

  

E-mail:
ding.zhang[at]riken.jp

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