Unconventional superconductivity at mesoscopic point contacts on the 3D Dirac semimetal Cd3As2

To obtain monophasic Cd3As2 (a topological insulator Cd3As2 and 3D Dirac semimetal) and investigate its transport property including point contact spectroscopy. Topological insulators in three dimensions are nonmagnetic insulators that possess metallic surface states (SSs) which may be driven into exotic phases with interesting properties.

: Pure and monophasic Cd3As2 is obtained which shows metallic behaviour of Cd3As2, which is consistent with previous reports. It is non-superconducting down to 2K and is also confirmed by magnetization measurements. Using a point contact (silver electrode) and Cd3As2 we observe a superconducting transition with a critical temperature (onset) greater than 6 K. This indicates that at the contact a non superconducting phase (Cd3As2) becomes superconducting while both both Ag and Cd3As2 are not superconductors. This unconventional superconductivity is due to injection of electrons by the Ag tip into the topological insulator (Cd3As2) and creating a superconducting region at the mesoscopic contact. This is the first report of such an experimental observation.

Contact details: 

Prof. Ashok Kumar Ganguli

Department of Chemistry