Physical phenomena in tiny superconducting cylinders made on ultrathin insulating quartz filaments

1. Physical phenomena in tiny superconducting cylinders made on ultrathin insulating quartz filaments Ying Liu, Pennsylvania State University, DMR-0202534 A hollow superconducting cylinder in an applied magnetic field, H. d is the cylinder diameter and F is magnetic flux. Building on the discovery [1] of the so-called destructive regime, the loss of superconductivity near certain magic magnetic flux values in tiny superconducting cylinders even at zero temperature, several new physical phenomena associated with this destructive regime have found. For example, a field-tuned, sharp (< 1G) transition from superconducting to normal state in zero-temperature limit, a novel quantum phase transition, was found. In addition, the homogeneous superconducting state away from the destructive regime appears to break down into highly unusual, bifurcating normal bands as the destructive regime is approached [2]. 1. Y. Liu et al., Science 294, 2332 (2001). 2. H. Wang et al., to appear in PRL (2005). c) a) b) d) a) Phase diagram of a tiny Al cylinder with d =150nm a destructive regime (superconductivity is not possible near F0/2 = 1x10-7Gcm2; b) A SEM picture of an Al cylinder (d=267nm); c) R(H) for an Al cylinder with d = 150nm; d) Schematic of the normal-band bifurcation.

2. Quantum phase transition in ultrathin, doubly connected superconducting cylinders Ying Liu, Pennsylvania State University, DMR-0202534 Education In the past year we have involved two graduate students, Haohua Wang and Neal Staley, and three undergraduate students, Nathan Kurz, Brian Coulter, and Ben Clouser to work on this project. Nathan is going to graduate school in physics now. Brian and Ben are in their junior year and are planning to go to graduate school. A student from a local high school, Rahul Krishna, has volunteered in our lab over the summer, working on ionic conduction through nanochannels prepared by pulling a quartz tube. Rahul works closely with Ben Clouser and Neal Staley. Undergraduate student Paul Carrigan pulling a quartz filament. Paul Graduated in 2003. Societal impact The work carried out under this program is fundamental science. It contributes to the broadening of knowledge base on solid state physics.