Tip-induced superconductivity in the topological crystalline insulator Pb$_{0.6}$Sn$_{0.4}$Te

Materials exhibiting nontrivial topological properties are in the focus of contemporary condensed matter physics and the emergence of exotic phases of matter from these materials is an outstanding issue. Pb$_{0.6}$Sn$_{0.4}$Te was recently known to be a topological crystalline insulator. In this talk, I will show that by forming a mesoscopic point-contact between a normal, non-superconducting elemental metal as a tip and Pb$_{0.6}$Sn$_{0.4}$Te as a sample, a superconducting phase is induced locally in a confined region under the point-contact. Interestingly, neither the tip nor the sample is a superconductor, but a prominent superconducting phase appears only under the point-contact at a high transition temperature $T_c$ that falls in a range between 3.7 K and 6.5 K. From experiments under different conditions with tips made up of different materials, both magnetic and non-magnetic, I will also discuss the nature of superconductivity.