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TT: Fachverband Tiefe Temperaturen

TT 49: Transport: Topological Semimetals 2 (jointly with DS, MA, HL, O)

TT 49.8: Vortrag

Mittwoch, 22. März 2017, 17:00–17:15, HSZ 204

Self-forming superconducting microstructures from Weyl semi-metals — •Maja D. Bachmann¹, Nityan Nair³, Felix Flicker³, Roni Ilan³, Nirmal J. Ghimire², Eric D. Bauer², Filip Ronning², James G. Analytis³, and Philip J.W. Moll¹ — ¹Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany — ²Los Alamos National Laboratory, Los Alamos, NM, USA — ³Department of Physics, University of California Berkeley, CA, USA

The non-trivial topology of the bulk bands in topological semi-metals protects new electronic states at the surface, such as the famous Fermi arc states. If a superconducting gap is induced in these materials, exotic electronic states are expected to appear at the interface such as zero-energy Majorana modes. These novel states provide insights into the topological aspects of electronic matter and are of interest for quantum coherent applications. Here we will present a new route to reliably fabricating superconducting microstructures from the intrinsically non-superconducting Weyl semi-metals NbAs and TaAs under ion irradiation. The large difference in the surface binding energy of Nb/Ta and As leads to a natural enrichment of Nb/Ta at the surface during ion milling, forming a superconducting surface layer (Tc~3.5K). Being formed from the target crystal itself, the ideal contact between the superconductor and the bulk enables an effective gapping of the nodes due to the proximity effect. Simple low energy ion irradiation may thus serve as a powerful tool to fabricate topological quantum devices from mono-arsenides, even on an industrial scale.