Broken time-reversal symmetry in a SQUID based on chiral superconducting Sr2RuO4

27th International Conference on Low Temperature Physics

Ishiguro, R.^1,2 ; Sakurai, T.^2 ; Yakabe, M.^2 ; Nakamura, T.^3,4 ; Yonezawa, S.^3 ; Kashiwaya, S.^5 ; Takayanagi, H.^2,6 ; Maeno, Y.^3

Center for Emergent Matter Science, RIKEN, Wako, Saitama

351-0198, Japan^1

Department of Applied Physics, Faculty of Science, Tokyo University of Science, Tokyo

125-8585, Japan^2

Department of Physics, Graduate School of Science, Kyoto University, Kyoto

6068502, Japan^3

Institute for Solid State Physics, University of Tokyo, Chiba

277-8581, Japan^4

National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba

305-8568, Japan^5

International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba

305-0044, Japan^6

关键词: Applied magnetic fields;    Broken time-reversal symmetry;    Magnetic interference;    Residual magnetic fields;    Superconducting junctions;    Superconducting state;    Time reversal symmetries;    Unconventional superconductors;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/2/022020/pdf
DOI  :  10.1088/1742-6596/568/2/022020

来源: IOP

【 摘 要 】

Unconventional superconductors involve not only gauge-symmetry breaking but also orbital- and spin-symmetry breaking. Superconducting Sr2RuO4 is known as a spin-triplet chiral p-wave and a topological superconductor with broken time-reversal symmetry (BTRS). Kerr-effect and muon-spin-rotation (pSR) measurements have shown that The bulk superconducting state of Sr2RuO4 features BTRS in The orbital part; hence, it is called The chiral state. BTRS in The response of superconducting junctions or SQUIDs would appear as The shifts of magnetic interference patterns. However, it is problematic to distinguish whether The shift originates in The residual magnetic field (trapped vortex) or The effects of BTRS. Here, we show that The magnetic interference patterns of a SQUID based on Sr2RuO4 are explicitly asymmetric with respect to The direction of both The bias current and The applied magnetic field; namely, there is no inversion symmetry. This indicates that The superconducting state of Sr2RuO4 undoubtedly breaks The time-reversal symmetry of The SQUID.