G. Sambandamurthy

Superconductivity-Related Insulating Behavior

We present the results of an experimental study of superconducting, disordered, thin films of amorphous indium oxide. These films can be driven from the superconducting phase to a reentrant insulating state by the application of a perpendicular magnetic field (B). We find that the high-B insulator exhibits activated transport with a characteristic temperature, TI. TI has a maximum value (TpI) that is close to the superconducting transition temperature (Tc) at B=0, suggesting a possible relation between the conduction mechanisms in the superconducting and insulating phases. Tp(I) and Tc display opposite dependences on the disorder strength.

Experimental evidence for a collective insulating state in two-dimensional superconductors

We present the results of an experimental study of the current-voltage characteristics in a strong magnetic field (B) of disordered, superconducting, thin films of amorphous indium oxide. As the B strength is increased superconductivity degrades, until a critical field (B(c)) where the system is forced into an insulating state. We show that the differential conductance measured in the insulating phase vanishes abruptly below a well-defined temperature, resulting in a clear threshold for conduction. Our results indicate that a new collective state emerges in two-dimensional superconductors at high B.

Nanowire Acting as a Superconducting Quantum Interference Device

We present the results from an experimental study of the magnetotransport of superconducting wires of amorphous indium-oxide having widths in the range 40-120 nm. We find that, below the superconducting transition temperature, the wires exhibit clear, reproducible, oscillations in their resistance as a function of magnetic field. The oscillations are reminiscent of those that underlie the operation of a superconducting quantum interference device.

Temperature and voltage driven tunable metal-insulator transition in individual W x V 1 − x O 2 nanowires

Results from transport measurements in individual

Melting of a 2D quantum electron solid in high magnetic field

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Synthesis, Spectroscopic Characterization, and Observation of Massive Metal—Insulator Transitions in Nanowires of a Nonstoichiometric Vanadium Oxide Bronze

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Single-Nanowire Raman Microprobe Studies of Doping-, Temperature-, and Voltage-Induced Metal–Insulator Transitions of WxV1–xO2 Nanowires

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Scalable Hydrothermal Synthesis of Free-Standing VO2 Nanowires in the M1 Phase

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Observation of pinning mode of stripe phases of 2D systems in high Landau levels.

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Fluctuations, dissipation, and nonuniversal superfluid jumps in two-dimensional superconductors

nanowires with varying extents of