SuperconductivitySuperconductivity

David KelleyDavid Kelley

ECPE 131ECPE 131

12-09-200212-09-2002

What is Superconductivity?What is Superconductivity?

State/Phase of matter with unique electrical, State/Phase of matter with unique electrical, magnetic, and thermal properties.magnetic, and thermal properties.

1.1. The Discovery of SuperconductivityThe Discovery of Superconductivity

2.2. Properties Exhibited by Superconductive MaterialsProperties Exhibited by Superconductive Materials

3.3. The BCS Theory of SuperconductivityThe BCS Theory of Superconductivity

4.4. High Temperature Superconductivity (HTSC)High Temperature Superconductivity (HTSC)

5.5. The Current State of Research in HTSCThe Current State of Research in HTSC

6.6. Development of Superconductive TechnologyDevelopment of Superconductive Technology

7.7. Obstacles of SuperconductivityObstacles of Superconductivity

8.8. Concluding RemarksConcluding Remarks

1. The Discovery of 1. The Discovery of Superconductivity Superconductivity

Onnes – Liquefaction of HeliumOnnes – Liquefaction of Helium Tests of electrical resistance of HgTests of electrical resistance of Hg

NomenclatureNomenclature

TTC C – Critical Temperature– Critical Temperature

HHCC – Critical Magnetic Field – Critical Magnetic Field

2. The Properties Exhibited by 2. The Properties Exhibited by Superconductive MaterialsSuperconductive Materials

Zero electrical resistance / Perfect conductionZero electrical resistance / Perfect conduction

Perfect Diamagnetism (The Perfect Diamagnetism (The Meissner EffectMeissner Effect))

Type II SuperconductorsType II Superconductors

Incomplete Meissner effectIncomplete Meissner effect

3. How Superconductivity Works3. How Superconductivity Works(The BCS Theory)(The BCS Theory)

Fritz London – ‘Giant Fritz London – ‘Giant Atom’Atom’

Cooper pairsCooper pairs

Scattering – Scattering – phononsphonons

No scattering – No scattering – Virtual PhononsVirtual Phonons

More on Cooper PairsMore on Cooper Pairs Equal but opposite momentum/opposite spinEqual but opposite momentum/opposite spin

Momentum pairMomentum pair

Equalibrium – 0 net momentumEqualibrium – 0 net momentum

Cooper pairs are dynamicCooper pairs are dynamic

Discrete energyDiscrete energy

Energy to alter the momentum of an Energy to alter the momentum of an electronelectron

Cooper pairs always have the same Cooper pairs always have the same momentummomentum

Energy to alter the momentum of a horde of Energy to alter the momentum of a horde of cooper pairscooper pairs

Bandgap and TBandgap and TCC

Discrete energy required to excite an Discrete energy required to excite an electron across bandgap (break cooper pair)electron across bandgap (break cooper pair)

Not all materials with large bandgaps Not all materials with large bandgaps become superconductive – cooper pairsbecome superconductive – cooper pairs

4. High Temperature 4. High Temperature Superconductivity (HTSC)Superconductivity (HTSC)

Limits of the BCS theoryLimits of the BCS theory

Bednorz and Muler: 30KBednorz and Muler: 30K

90K… 125K (3 groups)90K… 125K (3 groups)

If the BCS theory failed how does it work?If the BCS theory failed how does it work?

‘‘Giant Atom’ – New Electron Giant Atom’ – New Electron MediatorMediator

Common themes amongst Common themes amongst HTSCHTSC

Pervoskite – copper planesPervoskite – copper planes

5. The current state of research5. The current state of research

Mott insulators and dopingMott insulators and doping

Copper planes cause ‘resonating valence Copper planes cause ‘resonating valence bonds’ – antiparallel electron configurationbonds’ – antiparallel electron configuration

Non copper oxide HTSCNon copper oxide HTSC

Field effect doping superconductivity Field effect doping superconductivity

6. Superconductive Technology6. Superconductive Technology

Long distance power transmissionLong distance power transmission Energy storageEnergy storage InterconnectsInterconnects MRIMRI

MaglevMaglev

Particle AcceleratorsParticle Accelerators

7. Obstacles7. Obstacles

Critical temperatureCritical temperature Mechanical propertiesMechanical properties Technology InertiaTechnology Inertia No one knows how it really works?No one knows how it really works?

8. Concluding remarks8. Concluding remarks

Useful for magnetic and electric propertiesUseful for magnetic and electric properties

Must balance TMust balance TCC and H and HGG with other qualities with other qualities

No complete theory for HTSC, perhaps we No complete theory for HTSC, perhaps we missed something with low temp SCmissed something with low temp SC

Field effect dopingField effect doping

AcknowledgementsAcknowledgements Buckel, Werner. Superconductivity: Fundamentals and Applications. Buckel, Werner. Superconductivity: Fundamentals and Applications.

Weinheim, Germany: VCH Verlagsgesellschaft mbH, 1991.Weinheim, Germany: VCH Verlagsgesellschaft mbH, 1991. Iovine, John. “Superconductors.” Poptronics. July 2000. November, 2002.Iovine, John. “Superconductors.” Poptronics. July 2000. November, 2002.

<http://web7.infotrac.galegroup.com/itw/infomark/965/565/26215720w7/<http://web7.infotrac.galegroup.com/itw/infomark/965/565/26215720w7/purl=rc1_EAIM_0_A63667028&dyn=11!xrn_3_0_A63667028?purl=rc1_EAIM_0_A63667028&dyn=11!xrn_3_0_A63667028?sw_aep=uop_demo >sw_aep=uop_demo >

Kresin, Vladimir Z. and Stuart A. Wolf. Fundamentals of Superconductivity. Kresin, Vladimir Z. and Stuart A. Wolf. Fundamentals of Superconductivity. New York: Plenum Press, 1990.New York: Plenum Press, 1990.

Orlando, Terry, and Kevin A. Delin. Foundations of Applied Superconductivity. Orlando, Terry, and Kevin A. Delin. Foundations of Applied Superconductivity. Reading, Massachusetts: Addison-Wesley Publishing Company Inc., 1991.Reading, Massachusetts: Addison-Wesley Publishing Company Inc., 1991.

Pines, David, and Ulam Scholar. Understanding High Temperature Pines, David, and Ulam Scholar. Understanding High Temperature Superconductivity: Progress and Prospects. Center for Nonlinear Studies at Superconductivity: Progress and Prospects. Center for Nonlinear Studies at Los Alamost National Laboratory and Physics Department, University of Illinois: Los Alamost National Laboratory and Physics Department, University of Illinois: 10-28-02. <http://cnls.lanl.gov/Highlights/1997-06/html/June_97.html>10-28-02. <http://cnls.lanl.gov/Highlights/1997-06/html/June_97.html>

Superconductivity for Electric Systems. U.S. Department of Energy: 10-28-02. Superconductivity for Electric Systems. U.S. Department of Energy: 10-28-02. <http://www.eren.doe.gov/superconductivity/><http://www.eren.doe.gov/superconductivity/>

Vidali, Gianfranco. Superconductivity: The Next Revolution? Cambridge: Vidali, Gianfranco. Superconductivity: The Next Revolution? Cambridge: Cambridge University Press, 1993.Cambridge University Press, 1993.