Organic Superconductors

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Organic Superconductors At Extremes of High
Magnetic Field
Organic Superconductors At Extremes of High
Magnetic Field
C. H. Mielke Los Alamos National
Laboratory National High Magnetic Field Laboratory
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Organic Superconductors At Extremes of High
Magnetic Field
C. H. Mielke Los Alamos National
Laboratory National High Magnetic Field Laboratory
NHMFL
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(No Transcript)
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NHMFL Magnetic Field Capabilities

• Explosively Driven
• 145 T flux compression generator (3 kg
  detasheet)
• 800-1000 T fcg cylindrical symmetry (20 kg
  HMX-9501)
• 300 T Capacitor Driven exploding coils
• Controlled Waveform 90 MJ (650 MJ max)
• 60T 2 second controlled waveform
• 100T CW outsert CD insert 145 MJ (available 2004)
• Capacitor Driven 0.6-1.2 MJ (1.6 MJ max)
• 60T short pulse 6ms rise 40ms decay
• 50T mid-pulse 40ms rise 300ms decay
• DC Superconducting Magnets (to 20T)

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Fowler Flux compressors

• Max field of 180T
• 10mm to 20mm bore
• High homogeneity
• Sample cryostat are destroyed
• 3 kg of sheet explosive

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NHMFL Magnetic Field Capabilities

• Explosively Driven
• 145 T flux compression generator (3 kg
  detasheet)
• 800-1000 T fcg cylindrical symmetry (20 kg
  HMX-9505)
• 300 T Capacitor Driven exploding coils
• Controlled Waveform 90 MJ (650 MJ max)
• 60T 2 second controlled waveform
• 100T CW outsert CD insert 145 MJ (available 2004)
• Capacitor Driven 0.6-1.2 MJ (1.6 MJ max)
• 60T short pulse 6ms rise 40ms decay
• 50T mid-pulse 40ms rise 300ms decay
• DC Superconducting Magnets (to 20T)

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Multi-Stage Flux Compression Generators

• Russian Design MC1 FCG
• 800 to 1000 tesla
• 20 kg shaped explosive (PBX 9501) 95 HMX 9505
  and 5 Plastic bonder

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Multi Stage Flux Compression
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NHMFL Magnetic Field Capabilities

• Explosively Driven
• 145 T flux compression generator (3 kg
  detasheet)
• 800-1000 T fcg cylindrical symmetry (20 kg
  HMX-9505)
• 300 T Capacitor Driven exploding coils
• Controlled Waveform 90 MJ (650 MJ max)
• 60T 2 second controlled waveform
• 100T CW outsert CD insert 145 MJ (available 2004)
• Capacitor Driven 0.6-1.2 MJ (1.6 MJ max)
• 60T short pulse 6ms rise 40ms decay
• 50T mid-pulse 40ms rise 300ms decay
• DC Superconducting Magnets (to 20T)

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90 MJ of energy
1m
1.4 GW motor-generator
Specific Heat in a Kondo Insulator Jaime, et al,
Nature 405 (2000) 160
60 minutes between full field shots
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NHMFL Magnetic Field Capabilities

• Explosively Driven
• 145 T flux compression generator (3 kg
  detasheet)
• 800-1000 T fcg cylindrical symmetry (20 kg
  HMX-9505)
• 300 T Capacitor Driven (CD) exploding coils
• Controlled Waveform (CW) 90 MJ (650 MJ max)
• 60T 2 second controlled waveform
• 100T CW outsert CD insert 145 MJ (available 2004)
• Capacitor Driven 0.6-1.2 MJ (1.6 MJ max)
• 60T short pulse 6ms rise 40ms decay
• 50T mid-pulse 40ms rise 300ms decay
• DC Superconducting Magnets (to 20T)

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NHMFLs 100 T Multi-Shot Magnet
140 MJ of energy
Specifications
Design and Materials
100T peak field 15mm bore Pulse every hour
Insert Coil (2 MJ peak energy) (National
Science Foundation) CuNb Conductor MP35N
Sheet Zylon Fiber Reinforcement
Outer Coil (125 MJ peak energy) (Department of
Energy)
1 msec at 100T peak field
Coils 1 through 4 AL-60 Conductor 301 SS
Sheet Reinforcement wound on Nitronic-40
bobbin
10 msec above 75T
Coils 5 and 6 AL-15 Conductor Nitronic-40
Monolithic Reinforcement
2 second total pulse duration
Coil 7 Hard Cu Conductor 304 SS Monolithic
Reinforcement
One Meter
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NHMFL Magnetic Field Capabilities

• Explosively Driven
• 145 T flux compression generator (3 kg
  detasheet)
• 800-1000 T fcg cylindrical symmetry (20 kg
  HMX-9505)
• 300 T Capacitor Driven exploding coils
• Controlled Waveform 90 MJ (650 MJ max)
• 60T 2 second controlled waveform
• 100T CW outsert CD insert 145 MJ (available 2004)
• Capacitor Driven 0.6-1.2 MJ (1.6 MJ max)
• 60T short pulse 6ms rise 40ms decay
• 50T mid-pulse 40ms rise 300ms decay
• DC Superconducting Magnets (to 20T)

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60 tesla short pulse
0.6 MJ of energy
10 cm

• 6 milli-seconds to peak field
• Work-horse of the magnet lab
• Life-time of 500 full field shots

30 minutes between full field shots
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Normal Mode of Failure

• Causes minor damage
• He dewar tail
• Probe insert
• LN2 bucket (igloo cooler)
• Fault on lead end or sometimes in the 3rd layer
  midplane (due to fatigue of conductor)
• Audible report

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Short Pulse Stress Failure
0.8 MJ of energy
60 tesla magnet destroyed at 72 tesla
confinement failure
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Worth the hassle for condensed matter physics

• Extreme fields quantize quasi-particle orbits
• Split Energy Bands
• Suppress Superconductivity
• Drive magnetic transitions
• Reveal new states of matter
• Ect., ect., etc.

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Organic Superconductors
TetraMethylTetraSelenaFulvalene cloride
Tc1K k-BisEthyleneDiThio-TetraThioFulvalene Coppe
r ThioCynate Tc10K k-BisEthyleneDiThioTetraThi
oFulvalene copper DiCyanidBromide
Tc11.6K l-BisEthelyneDiThioTetraSelenaFulvalene G
allium TetraClorate Tc 5K

• First Organic Superconductor Discovered in 1979
• Initial Tc of 1K
• Q1-D salt
• Various categories
• Bucky Balls
• FET types
• Charge transfer salts

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Charge Transfer Salts begin with organic radicals

• BEDT-TTF based (ET for short)

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Effect of the Inorganic Anion
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Organic meets Inorganic
l-(BEDT-TSF)2GaCl4
Half of the unit cell
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The Unit Cell
a 18 Å b 16 Å c 8 Å
a 16 Å b 8 Å c 13 Å
l-(BEDT-TSF)2GaCl4
k-(BEDT-TTF)2Cu(NCS)2
Layer spacing is the important dimension
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The Fermi Surfaces
l-(BEDT-TSF)2GaCl4
k-(BEDT-TTF)2Cu(NCS)2
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Anisotropy of the Electronic System
k-(BEDT-TTF)2Cu(NCS)2
k-(BEDT-TTF)2Cu(NCS)2
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Molecular Corridor
l-(BEDT-TSF)2GaCl4
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Magnetic Breakdown in l-(BEDT-TSF)2GaCl4
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Magnetic Breakdown in k-(BEDT-TTF)2Cu(NCS)2
T 40 mK
T 650 mK
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Magnetic Breakdown
Pippard Magnetic Breakdown
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Exponential Growth of Breakdown Amplitude
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Forbidden Trajectories
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Angular Dependent Magnetoresistance
l-(BEDT-TSF)2GaCl4
B 42T (DC)
k-(BEDT-TTF)2Cu(NCS)2
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B
q
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Belly orbits show l salt to be more 3-D than k
Peak width is determined by the interlayer
transfer integral (t )
Quasi 2-D region w/B layers
C. Mielke, et. al. J. Phys. Cond. Mat., 13 (2001)
8325.
Tight-binding dispersion relation added to the
effective dimer model
J. Singleton, et. al. PRL, 88 (2002).
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Using G-L theory to estimate xz
xz 16Å
xz 5Å
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At T x 18 Å for l-(BEDT-TSF)2GaCl4
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k-(BEDT-TTF)2Cu(NCS)2 appears to be in the 2-D
limit so close to Tc we cant resolve it
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Superconducting Properties of l-(BEDT-TSF)2GaCl4a
nd k-(BEDT-TTF)2Cu(NCS)2
C. H. Mielke, J. Singleton, M-S Nam, N. Harrison,
C.C. Agosta, B. Fravel, and L.K. Montgomery, J.
Phys. Condens. Matter, 13 (2001)8325.
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Conclusions

• Creating very high magnetic fields can be
  exciting!
• By tuning the organic molecules the effective
  dimensionality of the system is readily changed
• Dimensionality is closely related to the
  superconducting properties

John Singleton (Oxford U. joining LANL in
July) Ross McDonald (LANL Postdoctoral Fellow 3-D
Fermi surfaces) Greg Boebinger, Dwight Rickel,
Neil Harrison (LANL) Mike (L. K.) Montgomery
(Indiana U. synthesis of organic SC) Department
of Energy and the National Science Foundation