Negative differential conductance in nano-scale normal metal/superconductor/normal metal junctions featuring Fe_1 + yTe_1 − xSe_x

Abstract

Iron-based superconductors have been the subject of intensive study due to their high transition temperature and intriguing physical mechanisms. We describe a unique experimental approach to fabricate nano-scale normal metal/superconductor/normal metal junctions involving microcrystals of Fe_{1  + y} Te_{1  − x} Se _x , for which we have observed a distinct phenomenon of negative differential conductance (NDC) dips along with multiple plateau features in differential conductance spectra. The evolution of the NDC dips and the plateau features is further explored as a function of both temperature and magnetic field, and their physical origin is discussed.

Keywords:

• iron-based superconductor
• nanostructures
• Andreev reflection
• electron transport

Acknowledgements

We thank Professor P. Hor for helpful discussions. Z.W. is supported by the State of Texas through the Texas Center for Superconductivity at University of Houston.

Additional information

Notes on contributors

Carlos Diaz-Pinto

Both authors contributed equally to this work.