Events at Physics |
Events on Thursday, June 11th, 2009
- R. G. Herb Condensed Matter Seminar
- Intriguing Magneto-transport Behavior in Nanostructured NbN Superconductors and in Nanowires of the NbSe<sub>3</sub> Charge Density Wave System
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Umesh Patel, Argonne National Lab
- Abstract: Superconducting nanostructures are highly desirable in future nanodevices and also provide a unique platform to search for new superconducting phenomena in confined geometries. I will describe a novel synthesis approach used to transform nanostructures of the charge density wave material NbSe3 into superconducting NbN and NbSe2 nanowires and nanoribbons. Subsequent four-probe magneto-transport studies on individual superconducting NbN nanostructures reveal an intriguing oscillatory behavior in the magnetoresistance and critical current. These oscillations can be understood within the framework of quantized magnetic flux cutting through phase coherent loops of superconducting grains composing the nanostructure. The size of the phase coherent grain loop sets the relevant parameter for the observed oscillation periods. Although the transverse dimensions of our NbN nanostructures are much larger than the superconducting coherence length, the voltage-current characteristics of these granular NbN nanostructures at low temperatures are remarkably reminiscent of those observed in one-dimensional superconductors where dissipation is associated with quantum phase slips (QPS). Our results highlight the complexity of probing QPS in superconducting nanostructures. In addition, I will report on transport studies of NbSe3 nanostructures where we observed a magneto-resistance peak at low magnetic fields related to confinement of electron trajectories at low temperatures.
- Host: Robert McDermott