2. Future of Superconductivity
Paul M. Grant
Science Fellow
EPRI

3. 1911 A Big Surprise!
Thus the mercury at 4.2 K has entered a new state, which, owing to its particular electrical properties, can be called the state of superconductivity
H. Kamerlingh-Onnes (1911)

4. Magnetic Susceptibility
-1/4  T
H off
H on
-1/4   T
H on
H on
Expected (Lenz’ Law)
Weird ! (Meissner Effect)

5. “Cooper’s Problem”
 = N(EF) V0

6. “Cooper Pairs”
California Style

7. BCS Origin of   = N(EF) V0
-/a
/a
-/2a
/2a
quasi-momentum (k)
Energy EF 4
N(EF) = 1/(dE(k)/dk) = 1/[2 {1-(EF/2)2}1/2]
E(k) = 2 cos(ka)
N(EF) ~ -1 ~
[ AUB d ]-1
 = N(EF) V0
V0 ~
A(UB) d

8. Strong Coupling (1) McMillan/Eliashberg Equation: “Coulomb Repulsion:”
“Dimensionless electron-phonon
Coupling Term:”

9. Strong Coupling (2) “Tunnel Spectral Term” e-p matrix element
deformation potential matrix element

10. TC vs Year |
1911
2001
1930
1950
1970
1993
1988
1987
1986
20 K
140 K
40 K
60 K
80 K
100 K
120 K
Absolute
Zero
Helium
Boils
Hydrogen
Nitrogen
Methane Hg
La-214
Y-123
Bi-2223
Tl-2223
Hg-1223
Nb Compounds
MgB2
p-C60

11. Theory Situation
“Gap” line
“Triple Point”
No complete quantitative theory exists (i.e., “computable”)
“Simple” superconductors can be dealt with by M-E quasi-quantitatively
TC for hex-Si was predicted
MgB2, C60, (SN)x can be “explained”
15 years after their discovery, there is still no accepted microscopic theory for layered copper oxide perovskites
“We may never know exactly what interactions play out at the triple point.” Bob Laughlin

12. Type II Superconductivity
 = / > 1/2
Irreversibility
Line
Meissner
Mixed
Normal
HC2
HC1
Magnetic Field TC
Temperature -M H
1/4p

13. Abrikosov Vortex LatticeH
Dipole
Force
FP = FP(0) [1-(T/TC)]n J
FLorentz
Type II Superconductor
in the Mixed State

14. Vortex Matter “The Party’s Over” Thermally activated
Tinkham, PRL 61, 1658 (1988)
Static Phase Diagram
Temperature
Magnetic Field
Dynamic Phase Diagram TC
HC2
HC1
FLorentz
Elastic Flow
Plastic Flow
Liquid Flow
Normal
Liquid
Glass
Solid
Bose Glass
Polymer Glass
Melting Line
Meissner State
SC Fluctuation
Regime
R/Rn = {I0[A(1-t)3/2/2B]}-2
T = T/TC
Thermally activated
flux flow possible
Showstopper for
“real high” TC

15. ac Losses H M

16. Superconductivity Yesterday
Magnetic Resonance Imaging
Philips
Tevatron
Fermi National Laboratory

17. Important Numbers in Superconductivity
Transition Temperature, TC Way below 300 K
Critical Current Density, JC A/cm2
Critical Magnetic Field, HC T
London Penetration Depth,  >1000 Å
Pippard Coherence Length,  >1000 Å
Mean Free Path, l – 5000 Å
G-L Parameter,  = /
NB! All these numbers depend on each
other. E.g., HC ~ TC ~ 1/

18. Metrics of Superconductors
Operating Temperature (~ 2/3 TC)
Irreversibility Field (~ 70% HC2)
Operating Current (~ 80% JC)
Wire/Cable Weight
Cryogenic Load (cooling watts/plug watts)
Cost ($/kAm)

19. Power Application Specs
Figure taken from:
T, H, Jc requirements roughly reflect those of current DOE Superconductivity Partnership Initiative Projects
T(K) =
H(T) =
1 - 4
Jc(A/cm2) =
154,000 – 192,000
7,000 – 231,000
R. D. Blaugher, NREL

20. Power Device Req’mts T (K) H (T) Jc (A/cm2) Motors/ Generators 30 4
100,000
Transformers 2
80,000
Current Limiters
Cables 77
0.5
70,000
Specifications roughly reflect requirements of present DOE Superconductivity Partnership Initiative projects. See

21. Merit Factor for Superconducting Wire:
Wire Cost Issues
Merit Factor for Superconducting Wire:
C/P = $/kAmp × meters
Wire
C/P
Cost Driver
NbTi (4.2 K, 2 T)
0.90
Materials (Nb)
Nb3Sn (4.2 K, 10 T) 10
Bi-2223 (25 K, 1 T) 20
Materials (Ag)
Y-123 (25 K, 1 T) 4
Capital Plant
Above data drawn from the following paper presented at the 1998 Applied Superconductivity Conference held in Palm Desert, CA. C/P adjusted from projected $50/kAm for Bi-2223 and $10/kAm for Y-123 wire at 77 K, self field, as their commercial goals to 25 K, 1 T.

22. Superconductivity Today
Frisbie Substation, Detroit, 2001

23. Gen I has Problems… Silver is one…
JC 12 K
> 3.6105 A/cm2
> 2.6105 A/cm2
> 1.6105 A/cm2
= 0 A/cm2

24. HTS Tape Gen II: It’s Coming!
“1-2-3 is Better” Y Ba
CuO
Pyramids
Chains
Planes
YBa2Cu3O7-y
TC = 93 K
JC > 106 A/cm2
JC > 105 A/cm2 (1 T)

25. Coated Conductors Generation II Wire
Biaxially Oriented Y-123
Out of Japan, LANL, ORNL
DOE/Industry Alliance to Commercialize

26. Frisbie Cable

27. Men at Work

28. Men at Work, II

29. Men at Work, III

30. Pull Visualization

31. Finding New Superconductors
“Advances in superconductivity
begin with the empirical search for new materials.”
Bednorz and Mueller,
Z. Phys., Sept., 1986
“No new superconductor was ever
found using theory.”
Berndt Matthias
“If you run across a strange metal, new or old,
it’s a good idea to cool it down…you might get
a surprise.
P. M. Grant

32. Nature, 1 March 2001
How was it ever missed!

33. Maybe It Wasn’t ! ? 39 32

34. Cost Issues: MgB2 Alfa Aesar
Assumptions/Givens:
JC = 100,000 A/cm2
IC = 2000 A/wire (Area = 2 mm2)
Non-Materials C/P = 0.11 $/kA•m (NbTi)
Alfa Aesar MgB2 Price Quote (10 kg)
750 $/kg (0.75 $/gm)
MgB2 Wire C/P
K, 1 T
The following calculation assumes an eventual non-materials basic manufacturing
cost (BMC) similar (in this case equal) to that of present commercially available NbTi
wire. 10 kg batch quote from Alfa Aesar on 8 March 2001.

35. The Nuclear/Hydrogen/Superconductivity
It’s 2015
A World at Peace
Global Climate at Risk
Continuing Industrialization Reaches All Corners of the Planet
The Nuclear/Hydrogen/Superconductivity
Economy at last!

36. Climate Friendly Energy
National Climate Change Technology Initiative (NCCTI – “Necktie”)
“Absolutely Zero GHG Emissions by 2050”
George W. Bush
MgB2
1/5/01
40 K
Cheap
Fall Issue, The Industrial Physicist
Tunnels
Fermilab
2 m Dia.
150 m Deep
Cheap

37. “The 60-fold Way”

38. “Little” Model TC ~ 400 K !!! = “hole-exciton” coupling
W. A. Little, Sci. Am. 212, 21 (1965)
“Conducting
Polyene Spine”
“Paired Holes”
= “hole-exciton” coupling
(“weak,” ~ 0.25)
“Polarizable
Side Groups”
”E” = “exciton energy”
(~ 2 eV, ~ 23,000 K)
TC ~ 400 K !!!

39. “The 60-fold Way” The separation between the electronic states
and vibrational modes of C60 exploited by
Schön et al. is just the sort of thing Little
had in mind in the 1960s when he proposed
his ‘excitonic’ model of superconductivity.

40. The Future 2028 Is “Room Temperature” Superconductivity
Possible? Why Not?
2028

41. Defense Drivers for Superconductivity
Many “weapons” need power…lots of it
Ships, planes, tanks, KE devices, …
Launch technologies
SC cables, generators, motors, storage…
Hardened Infrastructure
Everything underground
Power (electrical/chemical) superhighway
Maglev

42. R&D Road to 2020 Old materials (survey)
New materials (empirical, exotic)
Combinatorial chemistry (???)
Computational Chemistry & Physics
“Configuration Interaction”
Role of “dimensionality”
Luck !

43. “You can’t always get what you want…”

44. “…you get what you need!”

45. “Gap” line