Extreme Conditions Science Pressure, Field and Temperature

1. Extreme Conditions Science Pressure, Field and Temperature Stan Tozer National High Magnetic Field Laboratory June 26, 2009 Many thanks to: Eric Palm, Tim Murphy, Mika Kano, Dave Graf, Ju-Hyun Park, Kenny Purcell, Ryan Stillwell, Henri Radovan, Kristen Collar, Julia Bourg, Chuck Mielke, Chuck Agosta, Red Schwartz, John Ferrell, Daniel McIntosh, Ryan Newsome, Mike Pacheco & Stan Outland

2. Outline • Definition and units of pressure • Pressure cells for use in magnetic fields • Relevant material properties • Designing cells to meet your requirements • Pulsed field and microkelvin pressure studies • Safety

3. Pressure Provides a means to tune systems continuously, suppress or induce phenomena Biological systems require far smaller pressures to modify their behavior compared to “typical” metals Can be used to provide novel synthetic pathways Hydrostatic vs. uniaxial Pressure = Force/Area 103 bar = 1 kbar = 108 N m-2 = 0.1 GPa 1 kbar—Marianas Trench 1.37 x 103kbar—Mantle-core interface 3.64 x 103kbar—Center of earth 1 x 108 kbar--Center of sun 1017-1021kbar--Neutron Star

4. Science dictates design • Sample-solid/liquid/gas & volume required • Pressure range and degree of hydrostaticity • Magnetic fields • Temperature range • Rotation • Techniques-VIS, FIR, narrow band and MAS NMR, EPR, electrical transport, photoconductivity, heat capacity, SdH, dHvA, susceptibility • When will Walmart carry them?

5. Device/Pressure Range/Experimental volume/footprint • Large press—10 GPa, 1 cm3 working volume, New York City apartment. This area of high pressure physics resulted in the discovery of synthetic diamond. • Large volume piston-cylinder cell—4 GPa, 0.1 cm3, beer can • Bridgman cell—10 GPa, 0.003 cm3, Red Bull can • Indentor cell—5 GPa, 0.001 cm3, walnut to blackeyed pea • Diamond (SiC, sapphire) anvil cell, <1000 GPa, 10-5-10-9cm3, very small

6. ISSP cubic press

7. Large Volume Piston-Cylinder Cell • I. R. Walker RSI v70 p3402 (1999) • 3.5 GPa • Non-magnetic • Millikelvin temperatures • Design variations throughout Japan NHMFL Refinements • fiber optic to measure pressure via ruby line at temperature of interest • Smaller acorn bomb design that rotates in 25 mm diameter space • dHvA coils-6500 turn coils

8. NHMFL 3 GPa Acorn Bomb Single axis rotator for SCM1 7000 turn dHvA coils & fiber optic Ø1 mm x 1.5 mm sample space Locknut and thrust plate Ø 19 mm cell body-rotates in Ø25 mm

9. NHMFL Miniature piston-cylinder cell • Torque magnetometry • Resistivity • 1.5 grams total weight • Sample space Ø1mm x 2mm • Inspired byMiclea (MPI) design

10. Issues with Piston-cylinder cells and Intensifiers

11. Indentor Cell Kobayashi et al. RSI 78, 023909 (2007) Anvil lead configuration 0.86 gram indentor cell for heat capacity & torque magnetometry

12. Merrill-Bassett Diamond Anvil Cell (DAC)simple cell for Xray work

13. Basic mechanism of a DAC

14. Rapid morphing… DACs have morphed to allow experimentalists to: Achieve higher pressures Use techniques other than simple optics and xrays Change the pressure in situ Perform studied at very high temperature Combine with laser shock way

15. What you need to know to make a simple DAC

16. Materials Selectionfor cells used in magnetic fields • Thermal link to sample • Magnetic properties • Optical access • Electrical properties • Mechanical properties • Anvil/Piston--WC with Ni binders, diamond, Zirconia, SiC (moissanite), sapphire • Gaskets—BeCu (various grades), NiCrAl:B, MP35N, diamond/epoxy//ZYLON fiber • Gasket insulation—Alumina, cBN, diamond, epoxies • Cell bodies—aged BeCu172 (Ø3/8”), redrawn MP35N, NiCrAl:B (Japan), Parmax (Tecamax)

17. Pressure cells at NHMFL

18. Evolution from complex to simple

19. Reduce to the essentials Get out of the lab …found everywhere to tension structures Common turnbuckle with left and right-hand threads

20. Turnbuckle DAC Traditionally works in tension In compression • Alignment relies solely on machining and polishing tolerances • Minimal number of parts • Minimizes size by removing load mechanism • Inexpensive to machine • Optical and electrical studies • Smallest version rotates in MPMS

21. Samples and preparation • Cutting to shape—cleaving, EDM, coring, lapping • Eliminating damage—chemical etching, electropolishing, annealing • Contacts—masking, ohmic, low resistance • Leads & contacts—paints, solvents, indium, flattened wires & manipulation

22. gaskets • Gasket material—we have tried elephant tusk, warthog tusk, oyster shells, lobster shells, metals, plastics, ceramics, wood and many types of coatings • Preindenting & relocation • Insulation—alumina, diamond powder, cBNplus epoxy • Drilling or EDMing the hole—rule of thumb culet:Øhole:height::3:1:0.1

23. Gasket/sample assembly • Note preindented region • External electrical leads • Tuck flattened gold leads into corner • Don’t forget the ruby chips and pressure fluid Pressure fluids vary from NaCl, to mixtures of alchohols, to special oils to the inert gases. Consideration must be given to pressure and temperature range, required degree of hydrostaticity, reaction with the sample or contacts and ease of use.

24. Pressurizing the cell and installation in probe • Take data with increasing pressure • 50% success rate—maybe

25. Pressure Calibration • Manganin wire • InSb • Lattice constants • Ruby 1) R1=694.25nm 2) 0.365 nm/GPa @ all temperatures 3) Know the pressure at any temperature by measuring a reference

26. Pulsed Field High Pressure

27. Eddy Current Heating in Pulsed Fields

28. EC heating solution-plastic DACs • Take advantage of thermal conductivity of diamond • Use high strength fiber and diamond/epoxy to mimic metal gaskets • Use high strength plastic for body

29. Self-resonant tank circuit with tunnel diode oscillator (TDO) All plastic diamond anvil cell, ~30 kbar Coil ID ~300 m 360° rotator rf penetration depth at ambient and high pressure Single axis rotation in anvil pressure cells to 50 mK and up to 45 tesla (continuous) or to 450 millikelvin and up to 65 tesla (pulsed) Non-invasive method Increased safety Ø 8 mm

30. Some initial results --Choose your problem carefully --Break things… and then fix them --Proceed with utmost haste to your first failure

31. Safety Compressed gases/fluids are somewhat energetic upon sudden release • NEVER look down the barrel of a loaded pressure cell • Allow a piston-cylinder cell to relax after releasing the load • Do NOT use damaged parts (e.g. pistons) • Barreling or cracking-STOP • Machining of BeCu alloys • lasers

32. Extreme Condition Research a scientist

33. DAC size Material Rotation Plastic DAC Pressure-dependence of the zero-field splittings for the Fe8 single molecular magnet S. Takahashi, E. Thompson, S. Hill - Univ. of Florida S.W. Tozer - NHMFL A.G. Harter, N.S. Dalal - Florida State Univ.

34. References & Resources • I. R. Walker Review of Scientific Instruments 70 p3402 (1999). • The New Alchemists byR. Hazen • Vibrational Spectroscopy at High External Pressures by J. R. Ferraro • High-Pressure Techniques in Chemistry and Physics by W.B. Holzapfel & N. S. Isaacs • The Properties of Diamond ed. J.E. Field • Experimental Techniques in High-Pressure Research by W.F. Sherman & A.A. Stadtmuller • High Pressure Experimental Methods by M. Eremets • Research at High Pressures Gordon Conference • AIRAPT International High Pressure Conference

35. Getting Started stones materials BeCu172 Brush Wellman NiCrAl:B your favorite Japanese colleague MP35N Latrobe or Carpenter Steel, redrawing by G&S Titanium Parmax/Tecamax Boedeker Plastics ZYLON Toyobo • Almax • D’anvil cells • EasyLab • Almax

37. Apparatus for high pressure, high field, millikelvin studies Turnbuckle anvil cell Piston-cylinder anvil cell 4-probe resistivity Large volume piston-cylinder cell with dHvA coils

38. Equipment to load plastic DAC for TDO