Microsoft PowerPoint - Superconductivityalso decreases, but it reaches a constant value near
zero Kelvin due to impurities and imperfections in
the arrangement of atoms.
of resistivity (α > 0)
e-
RESISTANCE
3
@ T ≠ 0K EF + kT
@ T = 300K add kT = 25meV
( ) ( ) 1
1
E=0 → fBE = ∞
All bosons will condense on the lowest energy level in the solid.
( ) 1
1
• Their binding energy Eg ~ 10-3 eV
• Eg can be broken with
• As T decreases towards Tc, the
energy gap Eg becomes smaller.
• If T < Tc then Eg 0 and Cooper
pairs are released.
g(E) ~ E1/2 (spin ↑/spin ↓)
(e.g. Cooper pairs have a spin of 0)
• In a normal conducting material electrons
collide with the crystal lattice creating resistance.
• In superconductors @ low T the electrons pair
into a new boson (the Cooper Pair).
• When an electron of a Cooper pair collides
with the lattice, it creates a disturbance that
is transmitted solely to the other electron in
the pair through the crystal lattice. This long-
range interaction between electrons in the
Cooper pairs is because of the conservation
of linear momentum.
magnet, and the magnet
as being the critical field.
8
temperature, TC, these elements
•Limited applicability and
superconducting state.
vortices of superconducting
together and make the material insulating.
•For T < Tc the normal states become smaller
and the magnetic field that penetrates these
small regions does not encounter any
resistance, so the material shows
superconductive behavior.
about 300nm in type II superconductors .
Normal Regions Superconducting Region
Onnes.
superconductor.
4Kelvin (liquid helium).
temperature of 98 K
used to obtain a superconducting state.
Material Tc(K)
Gallium 1.1
Aluminum 1.2
Indium 3.4
Tin 3.7
Mercury 4.2
Lead 7.2
Niobium 9.3
Niobium-Tin 17.9
La-Ba-Cu-oxide 30
Y-Ba-Cu-oxide 92
Tl-Ba-Cu-Oxide 125
•“Space Efficieny”
superconductive cable.
•Transformers can be made smaller
and last longer.
almost 40% could be obtained with
the replacement of copper wires
with superconducting cables. 12
consumption in domestic manufacturing
• Using high-temperature superconducting
windings, this supermotor can produce
more power in less space, and use less
energy while doing it (high efficiency).
• Most cruise ships and large naval vessels
are switching to electric propulsion.
• These units are quieter than traditional
electric motors.
(July 2001).
generate much heat.
with most of today’s 32 or 64 bit processors.
• However, this four bit processor is 500
times faster than today’s common Intel
processor.
developing a superconducting chip. Japan
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<http://www.superconductors.org>
<http://www.hyperphysics.com>
& Sons Inc, 1996.
Technology. TAB Books, 1988.