SuperStuff

1
SuperStuff Lecture 4 http//www.physics.ubc.ca/
supercon/talks.html Informal Seminar Series JC
Séamus Davis jcdavis_at_ccmr.cornell.edu Every
Tue., 3.00 PM, AMPEL 311, Fall 2009 Independent
of the microscopic interactions leading to their
formation, supergasses, superfluids,
superconductors and supersolids exhibit the same
macroscopic quantum phenomena including
persistent currents, circulation (or flux)
quantization, quantized vortices, vortex
crystallization, London dynamics and Josephson
Effects. We will review, informally, the
history of these ideas, their experimental
validation, and the present state of research
into such superstuff.
2
Fermion
Macroscopic Quantum Systems


Superconductor Superfluid 4He Superfluid 3He
Superfluid 87Rb Superfluid ( e-Fermi
liquid) (Bose liquid) (Fermi liquid)
(Bose gas) (Fermi gas)
2e
1911 1934 1972 1995
2004/5
Verslagen van de Afdeeling Natuur-kunde der Kon.
Acad. van Wetenschappen te Amsterdam, pp. 1479,
28 April 1911.
H. Kamerlingh Onnes
3
London Electrodynamics

• Zero resistance
• Meissner-Oschenfeld Effect
• London Equations ( a la SC student)
• London Equations ( a la SF student)
• Flux(oid) Quantization
• London Moment

4
Superconductivity Zero Resistance

• Metallic R vs T
• e-p scattering (lattice interactions) at high
  temperature
• Impurities at low temperatures

R
Lattice (phonon) interactions
Electrical resistance
Impure metal
Residual Resistance (impurities)
R0
Pure metal
Temperature
TD/3
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Superconductivity Zero Resistance

• Superconducting R vs T

R
Superconductor
R0
Temperature
Tc
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Superconductivity Zero Resistance

• Impossible to measure zero
• Current flowing in a SC ring
• Nonzero resistance ? changing current ? changing
  magnetic field
• One such measurement ?

Magnetic field
I
Circulating supercurrent
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Superconductivity Zero Resistance
Magnetic field
MRI
Circulating supercurrent
8
Effects of Magnetic Field
Normal metal
Apply field
Field off
9
Effects of Magnetic Field
Perfect (metallic) conductor
Superconductor
Normal metal
Apply field
Apply field
Apply field
Cool
Cool
Field off
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Meissner-Oschenfeld Effect
Superconductor

• Inside B 0 ? perfect diamagnetism cM -1

Apply field
Cool
B/m0
-M
H
H
Hc
Hc
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London Equations

• Newtons law (inertial response) for applied
  electric field

Fritz Heinz London, (1935)
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London Equations

• Newtons law (inertial response) for applied
  electric field

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London Equations

• Newtons law (inertial response) for applied
  electric field

Fritz Heinz London, (1935)
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London Equations

• London Equations

15
Magnetic Penetration Depth - l

• Characteristic decay length
• m,e fixed l uniquely specifies the
  superconducting electron density ns

SC
B(z)
B0
z
l
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Lorentz invariant EM photons develop mass

• Characteristic decay length
• m,e fixed l uniquely specifies the
  superconducting electron density ns

SC
B(z)
B0
z
l
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Mystery of the weak force

• Gravity pulls two massive bodies (long-ranged)
  1/r2 photons infinitely long lived
• Electric force repels two like charges
  (long-ranged) 1/r2 gravitons infinitely long
  lived
• Weak force pulls protons and electrons
  (short-ranged) acts only over 1016 cm extremely
  short lived

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Super Condensate Throughout Universe Tc1036K

• There is something filling our Universe
• It doesnt disturb gravity or electric force
• It does disturb weak force and make it
  short-ranged
• What is it??

19
Like a superconductor

• In a superconductor, EM field gets repelled (M-O
  effect), but penetrates only over lL
• ? EM Fields become short-ranged
• Imagine a physicist living within a
  superconductor
• Finally figured out
• magnetic filed must actually be long-ranged
• there must be mysterious charge-two condensate in
  her Universe
• But she doesnt know what the condensate is, nor
  why it condenses
• Doesnt have enough energy to break up Cooper
  pairs or reach Vc

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Like a superconductor

• In a superconductor, EM field gets repelled (M-O
  effect), but penetrates only over lL
• ? EM Fields become short-ranged
• Imagine a physicist living within a
  superconductor
• Finally figured out
• magnetic filed must actually be long-ranged
• there must be mysterious charge-two condensate in
  her Universe
• But she doesnt know what the condensate is, nor
  why it condenses
• Doesnt have enough energy to break up Cooper
  pairs or reach Vc
• Thats the stage where we are with universe!

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London Equations (Macro. Quantum POV)
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London Equations (Macro. Quantum POV)
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London Equations (Macro. Quantum POV)
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London Equations (Macro. Quantum POV)
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Fluxoid Quantization
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Fluxoid Quantization
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Flux Quantization
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Flux Quantization
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London Moment
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Type II Superconductors (x lt l)
Normal state cores
Superconducting region
H
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Spectroscopic Imaging STM
Image dI/dV(r,EO.25mV)
0 25nm
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SuperStuff Informal Seminar Series JC Séamus
Davis jcdavis_at_ccmr.cornell.edu
http//people.ccmr.cornell.edu/jcdavis/ Every
Tue., 3.00 PM, AMPEL 311, Fall 2009 NEXT
WEEK NO Lecture!!!