Superconductivity: how it changed my life and how it has already touched your life

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Superconductivity how it changed my life and
how it has already touched your life

• Cathy Foley

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Me at school
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25 years later ..... Now the basis of white
LEDs Energy efficient replacement for light
bulbs?
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InN nanowires- Infra-red LED?

• IBM latest research
• Next electronics?

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CSIRO

• 24.5 years
• Solid state and materials physics
• Fundamental Science
• Applications of Science
• Travel
• Network with people around the world
• Full and rich life

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18 March 1987
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15-17 AUGUST 1969
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Where it all began!
In 1911
Heike Kamerlingh Onnes Noble Prize in Physics in
1913 Worked out how to cool things to very low
temperatures- liquid helium -270 oC
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-269 oC
-269.2 oC
-269.4 oC
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Helium -270 oC 30-80/litre Difficult to handle
Liquid nitrogen -200 oC 0.13/litre Handle like
boiling water
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Property 1 At a critical temperature loses all
resistance to the flow of electricity

• Superconductivity breaks down above Tc, Ic, Bc.

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Property 2 Magnetic fields cant penetrate a
superconductor
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Property 3 Can make small structures that are
sensitive to magnetic fields
Superconductor 2
Superconductor1
Superconducting tunnel current
Gap - 3 ?m LTS -1- 9 nm HTS
1 nm junction width
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Vitaly L. Ginzburg
2003
Alexei A. Abrikosov
Anthony J. Leggett
for pioneering contributions to the theory of
superconductors and superfluids
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What is superconductivity?

• Property of lots of materials
• Only demonstrated if the material is cooled
  below
• a critical temperature
• Some think every thing is a superconductor,
• we just cant get cold enough

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Transition Temperatures of Superconductors in
Pure Form
 
Element Tc, oK Compound Tc,
oK _______________________________________________
_____ Al 1.2 Nb3Al0.8Ge0.2 20.1 Cd 0.5 Nb3Sn
18.1 Ga 1.1 Nb3Al 17.5 In 3.4 Nb3Au 11.
5 La(?) 4.8 Nb3N 16.0 La(?) 4.9 M0N 12.0 P
b 7.2 V3Ga 16.5 Hg(?) 4.2 Nb3Ge 23.2 Hg(?)
4.0 Mo 0.9 _________________________________
______ Nb 9.3 HTS Compound Os 0.7 ___________
____________________________ Rh 0.5 Ta 4.5 La1.
85Ba0.15CuO4 40 Tc 8.2 YBa2Cu3O7-x 98 Tl 2
.4 HgBa2CuO4x 94 Th 1.4 Bi-Sr-Cu-O up to
115 Sn 3.7 Tl-Ba-Ca-Cu-O up to
125 Ti 0.4 YCaBa4Cu5(NO3)0.3(CO)0.7O11 82 W 0.0
1 U(?) 0.6 Medium Temperature MgB2
40 U(?) 1.8 V 5.3 Zn 0.9 Zr 0.8  
Nictides 30
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High School level BCS theory to explain
superconductivity
















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Normal Conduction of electricity
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e



Lattice distortion around an electron causes an
increase in positive charge density that will
propagate along the lattice with the cation
vibrations
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Animation of Cooper pairs
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Think of the conductor as a jungle gymbut
shaking

• Very difficult for a person to climb through!
• Especially if they are in a hurry!
• So, it is with electrons - constantly colliding
  with vibrating atoms because of the heat within
  the lattice.
•  

e
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To solve this problem..

• Imagine trying to get through a crowd of dancing
  people.
• Solution Convince the person ahead of you to
  lift you up and then, as the next person
  sees what's happening, the crowd lets you
  body-surf across the top of them.
• Similar to what happens when 2 electrons team
  up!

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Superconducting currents?

• The first electron convinces the next atom that
  you deserve special treatment.
• Once the process starts, everyone joins in and
  you begin moving forward effortlessly.
• The person-to-person exchange represents the 2
  electrons. And, your body represents the
  electrical charge.

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How to not get dropped

• There is, however, one small catch. Since the
  crowd is so active, you must first slow down the
  dancing so they can grab you as you arrive
  overhead.
• This is done by cooling the atoms to very low
  temperatures. The fast dance now becomes a slow
  dance. So our chances are much better to get a
  free ride across the room.
• This is superconductivity.

Slow down
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High Temperature Superconduction Big Problem

• BCS theory predicts theoretical maximum Tc of
  around 30-40K (-230oC)
• Above this, thermal energy causes electron-phonon
  interactions to be too highly energetic to allow
  formation of or sustain Cooper pairs.
• 1986 saw the discovery of high temperature
  superconductors which broke this limit (the
  highest known today is in excess of 150 K)
• It is in debate as to what mechanism prevails at
  higher temperatures, as BCS cannot account for
  this.

You can get your own Nobel Prize if you figure
this out!
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Room Temperature? 300K
FeAs (2008)
MgB2 (2001)
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Mineral Exploration
Submarine Detection
Oil Exploration
Quantum Computers
Metal Detector
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Biomagnetism
Electrode-less cardiograms
Magnetoencephalography
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Metal Detection

• Approached by Japanese Food Industry Broken
  hypodermic needles in blocks of meat a problem.
• Australian Food Industry Stainless steel (SS)
  particles in food difficult to detect.
• Majority of packaging machines are made from SS.

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Transport Maglev train - Shanghai
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OceanMAG

• Ability to map the ocean currents for use in
  climate and weather predictions/study
• Mapping the sea and sub-sea bed to discover
  mineral and oil deposits
• Develop a relationship between ocean gradients
  and oil and mineral deposits

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Other weird and wonderful applications

• SQUIDs in Space
• Gravitational Wave Detector
• Underwater Magnetic Detector
• Mind Readers
• Bolometric Mixers for Terahertz Applications
• Immunoassays using Magnetic Labels
• Quantum Computers

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Mind readers?
Macquarie University Linguistics Department
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THz Image obtained using an HTS JJ detector
Terahertz Imaging

• Security searches
• Imaging
• Improving mobile phone coverage
• Medical imaging of cancer

The THz imaging measurement bench. The
superconducting detector is mounted in a liquid
He cryostat facing the THz transparent window.
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?
Exponentially faster computers based on quantum
mechanics
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All in a days work

• Experiments
• Report writing
• Contracts
• Other writing
• Planning
• Talking
• Reading
• Travelling
• Budgets
• People issues
• Media

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Travel is great!
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Being a Scientist

• I could not imagine having any other job
• Every day is different and exciting
• I get to work with people, expensive equipment,
  be part of Australias innovation engine house
• I am making a difference..

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What I want you to take away from today!

• Tell your folks that CSIRO does research to
  benefit Australia- and their scientists are
  really cool!
• One day superconductivity will touch your life-
  it may have already
• Basics on superconductivity
• You too could win a Nobel prize
• I told you how to..