High T c Superconductors in Magnetic Fields. T. P. Devereaux. Kamerlingh Onnes, 1913 Nobel Prize for Discovery of Superconductivity in Mercury. Theory of Superconductivity by Bardeen, Cooper, and Schrieffer Earns Nobel Prize in 1972. Most successful many-body theory. Quantum Coherent State.
T. P. Devereaux
Most successful many-body theory.
Quantum Coherent State
Top speed: 552 km/hr
US Navy: 5,000 HP*
In-place in Detroit.*
*American Superconductor Corp.
<- Resistivity of Pure Copper
Electrons swirl in magnetic field – increased kinetic energy kills superconductivity.
SOLUTION: Magnetic field kills superconductivity in isolated places -> VORTICES (swirling “normal” electrons)
Apply current: Lorentz force causes vortices to move -> Resistance!
Du2= kBTy(L-y)/FL~ kBT/F
String is floppier at higher T -> vortex “liquid”
2) Planar Structure
“pancake” vortices in layers weakly coupled
Decreased string tension -> vortex decoupling
- protein folding, weather simulation, cosmology, chaos, avalanches, marine pollution, other non-equilibrium phenomena.
At low T, lattice forms with “defects”.
At higher T, lattice “melts”.
At low T, a few pins can stop whole “lattice”.
At larger T, pieces of “lattice” shear away.
Columns of defects are effective at pinning vortices.
But “channels” of vortex flow proliferate at larger fields.
But too much splaying and vortices cannot accommodate to defects.