Education : The award allows to support three graduate and five undergraduate students.

1. Quantum transport in one and two dimensional superconductorsAndrey Rogachev, University of Utah, DMR 0955484 Superconductor-Insulator Transition in 1D. Physical Review Letters (2012).We used advanced electron beam lithography with negative resist to fabricate very narrow (width 9-10 nm) MoGe nanowires (upper figure). We observed that the wires undergo a superconductor-insulator transition that can be induced by the reduction of the cross sectional area of the wires or by an external magnetic filed (lower figure). This is the first observation of the quantum (zero-temperature) phase transition in long one-dimensional superconductors. We found that contrary to many theoretical predictions the transition is governed by local properties of nanowires. Interplay of superconductivity disorder and magentic doping in 2D films. Physical Review B (2012).We studied the effect of magnetic doping with Gd atoms on the superconducting properties of amorphous MoGe films. We observed that in uniform films deposited on amorphous Ge, the pair-breaking strength of magnetic impurity strongly decreases with film thickness initially and saturates at a finite value in films with thickness below the spin-orbit scattering length. Surprisingly, in films deposited on SiN the pair-breaking strength becomes zero. This anomalous behavior is likely related to a granular morphology of the films that was detected by atomic force microscopy with a carbon nanotube tip. Admittance spectroscopy study of polymer diodes in small magnetic fields. Journal of Applied Physics (2012). It was recently discovered that small magnetic field can enhance current and light output of Organic Light Emitting Diodes. We performed the first systematic study of the frequency dependence of this effect. We observed two relaxation processes with distinct time scales that are influenced by the magnetic field. We attribute one of the processes to a monomolecular recombination and another to a electron-hole bimolecular recombination. Remarkably, we found rather large (4.5 %) magnetoconductance at our highest studied frequency (10 MHz).

2. Quantum transport in one and two dimensional superconductorsAndrey Rogachev, University of Utah, DMR 0955484 Education:The award allows to support three graduate and five undergraduate students. Hyunjeong Kim, graduate student, defended PhD in 2012 (upper photo), project: superconductor – insulator transition in 1D and 2D. Dieter Bevans, undergraduate student, Physics bachelor degree 2012; research project - the current noise spectroscopy of organic light emitting diodes. Dieter has been accepted to the graduate program of the Scripps Institution of Oceanography (UCSD). Kevin Devenport, undergraduate student, Physics bachelor degree 2012; research project AC transport in organic single crystal transistors. Kevin was a recipient of Undergraduate Research Opportunity (UROP) award in spring of 2012. Jordan Brown: Physics bachelor degree 2012. Research Project: Compact cryostat Derek Strasters: undergraduate junior student. Research project : Admittance spectroscopy study of Alq3 in small magnetic fields. James Skowronek, undergraduate senior student. Research project: Effect of cross sectional geometry on Tc in superconducting nanowires. James is a recipient of UROP award in fall of 2012. Outreach: PI chaired the physics section at the annual Utah UROP conference. Graduate student Shirin Jamali served as a judge at the Utah Science Olympiad (lower photo).