Observation of triplet superconductivity in CoSi₂/TiSi₂ heterostructures

Shao-Pin Chiu^1*, C. C. Tsuei^2,3, Sheng-Shiuan Yeh^1,4, Fu-Chun Zhang⁵, Stefan Kirchner^6,7, Juhn-Jong Lin^1,8

¹Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
²Thomas J. Watson Research Center, IBM, Yorktown Heights, NY 10598, USA
³Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
⁴International College of Semiconductor Technology, National Yang Ming Chiao Tung Universty, Hsinchu 30010, Taiwan
⁵Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
⁶Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027, China
⁷Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China
⁸Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan

* Presenter:Shao-Pin Chiu, email:spchiu@nycu.edu.tw

Spin-triplet superconductivity is of considerable interest to fundamental research and quantum technological applications. Here we report our observation of triplet pairing in nonmagnetic CoSi₂/TiSi₂ heterostructures on silicon. CoSi₂ is a superconductor (S) with a sharp superconducting transition at T_c ≈ 1.5 K, while TiSi₂ is a normal metal (N). We investigate conductance spectra of both CoSi₂/TiSi₂ S/N junctions and T-shaped CoSi₂/TiSi₂ superconducting proximity structures. Below T_c, we observe (i) a narrow zero-bias conductance peak on top of a broad hump, accompanied by two symmetric side dips in the S/N junctions, (ii) a narrow zero-bias conductance peak in T-shaped structures, and (iii) hysteresis in the S/N junction magnetoresistance. These three independent and complementary observations point to chiral p-wave pairing in CoSi₂/TiSi₂ heterostructures. The excellent fabrication compatibility of CoSi₂ and TiSi₂ with current silicon-based integrated-circuit technology suggests their potential use in scalable quantum-computing devices.

Keywords: triplet superconductivity, CoSi₂/TiSi₂ heterostructure, conductance spectra, S/N junction, T-shaped structure