Integrated Nanostructured Systems

Quantum transport in nanostructures; nanoelectronics; condensed matter physics at low temperatures.

Our experimental research group studies physical properties of low dimensional condensed matter systems. We use advanced nanofabrication techniques combined with controlled sample growth to design and develop sub-micron devices. These devices are used to explore microscopic mechanisms that influence and/or dictate the fundamental physical properties at the nanometer scale level.

We explore electron transport in superconducting wires, rings, nanotubes, nanotube quantum dots and graphene atomic layers under extreme physical conditions: ultra low temperatures (10 mK), high magnetic fields (16 T) and a.c. electric fields (~GHz). Some of our physics interests include quantum phase transitions (e.g. superconductor-insulator transition), conduction in superconducting wires, Kondo effect versus superconductivity in nanotubes, microwave spectroscopy to study collective phases in graphene monolayers, superconducting films etc.

Dilution Refrigerator and He-3 refrigerator with superconducting magnets Electron beam evaporator for non-magnetic materials.

R. Crane, N. Peter Armitage, A. Johansson, G. Sambandamurthy, D. Shahar and G. Gruner, "Survival of superconducting correlations across the 2D superconductor-insulator transition: A finite frequency study" Phys. Rev. B 75, 184530 (2007).

R. Crane, N. Peter Armitage, A. Johansson, G. Sambandamurthy, D. Shahar and G. Gruner, "Fluctuations, dissipation, and nonuniversal superfluid jumps in two- dimensional superconductors", Phys. Rev. B 75, 094506 (2007).

Y. P. Chen, G. Sambandamurthy, Z. H. Wang, R. M. Lewis, L.W. Engel, D. C. Tsui, P. D. Ye, L. N. Pfeiffer and K. W. West, "Melting of a 2D quantum electron solid", Nature Physics 2, 452 (2006).

G. Sambandamurthy, A. Johansson, E. Peled, D. Shahar, P. Bjornsson and K. A. Moler, "Power law resistivity behavior in 2D superconductors across the magnetic field-tuned superconductor-insulator transition", Europhysics Letters 75, 611 (2006).

A. Johansson, N. Stander, E. Peled, G. Sambandamurthy and D. Shahar, "Angular dependence of the magnetic-field driven superconductor-insulator transition in thin films of amorphous indium-oxide", Available at: http://xxx.lanl.gov/abs/cond-mat/0602160

G. Sambandamurthy, Z. Wang, R.M. Lewis, Y. P. Chen, L.W. Engel, D.C. Tsui, L.N. Pfeiffer and K.W. West, "Pinning mode resonances of new phases of 2D electron systems in high magnetic fields", Solid State Communications 140, 100 (2006).

A. Johansson, G. Sambandamurthy, N. Jacobson, D. Shahar and R. Tenne, "Nanowire Acting as a Superconducting Quantum Interference Device", Phys. Rev. Lett. 95, 116805 (2005).

8. G. Sambandamurthy, L. W. Engel, A. Johansson, E. Peled and D. Shahar, "Experimental Evidence for a Collective Insulating State in Two-dimensional Superconductors", Phys. Rev. Lett. 94, 017003 (2005).

G. Sambandamurthy, L. W. Engel, A. Johansson and D. Shahar, "Superconductivity-Related Insulating Behavior", Phys. Rev. Lett. 92, 107005 (2004).

G. Sambandamurthy, K. Das Gupta and N. Chandrasekhar, "Effect of granularity on the insulator-superconductor transition in ultra thin Bi films", Phys. Rev. B 64, 014506 (2001).