Milestones and new challenges in nanoscopic superconductors

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 (lt 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)
d)
b)
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 (d267nm) 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.