Organic Superconductors At Extremes of High Magnetic Field

1. 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

2. Organic Superconductors At Extremes of High Magnetic Field C. H. Mielke Los Alamos National Laboratory National High Magnetic Field Laboratory NHMFL

4. 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 outsertCD 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)

5. “Fowler” Flux compressors • Max field of ~180T • 10mm to 20mm bore • High homogeneity • Sample & cryostat are destroyed • 3 kg of sheet explosive

6. 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 outsertCD 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)

7. 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

8. Multi Stage Flux Compression

9. 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 outsertCD 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)

10. 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

11. 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 outsertCD 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)

12. NHMFL’s 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

13. 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 outsertCD 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)

14. 0.6 MJ of energy 60 tesla “short pulse” • ~6 milli-seconds to peak field • Work-horse of the magnet lab • Life-time of ~500 full field shots 10 cm 30 minutes between full field shots

15. 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

16. 0.8 MJ of energy Short Pulse Stress Failure 60 tesla magnet destroyed at 72 tesla “confinement failure”

17. 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….

18. Organic Superconductors TetraMethylTetraSelenaFulvalene cloride Tc=1K k-BisEthyleneDiThio-TetraThioFulvalene Copper ThioCynate Tc=10K k-BisEthyleneDiThioTetraThioFulvalene copper DiCyanidBromide Tc=11.6K l-BisEthelyneDiThioTetraSelenaFulvalene Gallium 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

19. BEDT-TSF based (BETS for short) Charge Transfer Salts begin with organic radicals BEDT-TTF based (ET for short)

20. Effect of the Inorganic Anion

21. Organic meets Inorganic l-(BEDT-TSF)2GaCl4 Half of the unit cell

22. 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

23. The Fermi Surfaces l-(BEDT-TSF)2GaCl4 k-(BEDT-TTF)2Cu(NCS)2

24. Anisotropy of the Electronic System k-(BEDT-TTF)2Cu(NCS)2 k-(BEDT-TTF)2Cu(NCS)2

25. Molecular Corridor l-(BEDT-TSF)2GaCl4

26. Magnetic Breakdown in l-(BEDT-TSF)2GaCl4

27. Magnetic Breakdown in k-(BEDT-TTF)2Cu(NCS)2 T = 40 mK T = 650 mK

28. Magnetic Breakdown Pippard Magnetic Breakdown

29. Exponential Growth of Breakdown Amplitude

30. Anomalous Trajectories are due to Stark Quantum Interference Forbidden Trajectories

31. Angular Dependent Magnetoresistance l-(BEDT-TSF)2GaCl4 B = 42T (DC) k-(BEDT-TTF)2Cu(NCS)2

32. B q

33. 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).

34. Using G-L theory to estimate xz xz ≈ 16Å xz ≈ 5Å

35. At T* x ≈ 18 Å for l-(BEDT-TSF)2GaCl4

36. k-(BEDT-TTF)2Cu(NCS)2 appears to be in the 2-D limit so close to Tc we can’t resolve it

37. Superconducting Properties of l-(BEDT-TSF)2GaCl4and 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.

38. 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