Scanning tunneling spectroscopic studies of low-dimensional electronic systems.

Low dimensional systems are known to exhibit interesting properties different form their bulk counterparts. In this talk, I will present our studies on two interesting low dimensional systems: zero dimensional superconductors and two dimensional graphene.  
Superconducting properties are known to undergo drastic changes as the system size is reduced below the bulk characteristic length scales. I will present our results of finite size effects on the superconducting properties in nanostructured thin films of Nb and Pb as a function of particle size1,2. In addition I will demonstrate that the measurement of single, isolated superconductors by scanning tunneling spectroscopy, opens up the possibility to explore interesting effects, hitherto inaccessible in ensemble averaged systems. These include the role of superconducting fluctuations and the occurrence of shell effects which cannot be observed from bulk measurements3. 

In the second part of my talk, I will show how the quasiparticle chirality can be probed at the nanoscale using an STM on epitaxial graphene4. 


References:

1. Phys. Rev. Lett. 95, 147003 (2005).

2. JPCM. 21, 205702 (2009).

3. arXiv:0904.0354, Bose et al,(submitted)

4. Phys. Rev. Lett. 101, 206802 (2008), New J. of Physics (in press) arXiv:1001.3058