1 / 46

The effect of 3 He impurity on supersolid

The effect of 3 He impurity on supersolid. E. Kim , Korea Advanced Institute of Science and Technology J. T. West, X. Lin, and M. H. W. Chan Penn State University J. S. Xia University of Florida. Outline. NCRI Low 3 He concentration mixtures in Vycor glass

norman-kemp
Télécharger la présentation

The effect of 3 He impurity on supersolid

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The effect of 3He impurity on supersolid E. Kim, Korea Advanced Institute of Science and Technology J. T. West, X. Lin, and M. H. W. Chan Penn State University J. S. Xia University of Florida

  2. Outline • NCRI • Low 3He concentration mixtures in Vycor glass • The effect of 3He in open cylindrical geometry

  3. Torsional oscillator ideal for detection of superfluid mass Be-Cu Torsion rod I : rotational inertia of torsion cell K: torsion constant of the torsion Rod Torsion cell containing helium Change of rotational inertia, I, can be detected by increase (or decrease) of the resonant oscillation period, o. Drive Detection

  4. Non-Classical Rotational inertia A. J. Leggett I(T)=Iclassical[1-fs(T)]

  5. We find evidence of superflow in bulk solid 4He and solid 4He in Vycor glass with pore diameter of 7nm and in porous gold with pore diameter of 490 nm.

  6. Reppy group • - Annealing Effect & Disorder effect (47% NCRIF) • Shirahama group • - NCRI and weak annealing effect • Kubota group • - Solid helium under rotation • Kojima group • - Frequency dependence & hysteresis Non-classical rotational inertia has been reproduced by

  7. Recent Experiments … and more questions to the nature of supersolid Non-Classical Rotational Inertia Excess Heat Capacity Anomaly (Xi and Chan) Ultrasound Anomaly (Goodkind) Pressure driven DC Flow: No flow Annealing Effect & confining effect 2nd sound measurement ? No anomaly in Pm Superfluid flow in grain boundaries Shear modulus at low temperatures

  8. Role of Defects? What kind of defect is responsible for the various NCRI values? What we can learn from 3He impurity effect?

  9. 4He solid diluted with a low concentration of 3He E. Kim & M.H.W. Chan Nature 427, 225 (2004) -*[ns] Data shifted vertically for easy comparison *=971,000ns

  10. Effect of 3He impurities Supersolid fraction [%]

  11. ‘Bulk’ 4He solid diluted with a low concentration of 3He (85ppm) at 60 bar

  12. Three torsional oscillators

  13. Channel width=0.5cm (ID=1.27cm OD=1.77cm) 3.25cm The effect of 3He impurity 3.0cm Resonant frequency=156Hz Tc~85mK Supersolid fraction at 51 bars =10/11000 ~ 0.1%

  14. 47ppb 3He in solid 4He at 55bars 0.76cm Resonant frequency:783Hz, Q~1x106 Open cylinder (no annular channel) Torsion cell Tc~105mK , Supersolid fraction 2.3ns/1100ns~0.2%

  15. 47ppb 3He in solid 4He at 55bars Resonant frequency:783Hz, Q~1x106 Open cylinder (no annular channel) Tc~105mK , Supersolid fraction 2.3ns/1100ns~0.2%

  16. 99ppb 3He in solid 4He at 60bars Tc~140mK and Supersolid fraction 3.5ns/1110~0.3%

  17. 150ppb 3He in solid 4He Resonant frequency:783Hz, Q~1x106 Open cylinder(no annular channel) Tc~140mK and Supersolid fraction 4ns/1110~0.36%

  18. 200ppb 3He in solid 4He at 61bars Tc~ 150mK and Supersolid fraction ~0.36% Supersolid fraction is smaller than that observed in annular channel.

  19. 200ppb 3He in solid 4He at 61bars Tc~ 150mK Supersolid fraction ~0.3% Supersolid fraction is smaller than that observed in annular channel.

  20. Annular cell Vs. Open cell

  21. 3He effect in solid 4He Even though supersolid fractionis sensitive to the geometry and thermal history, The effect of 3He on the onset temperature is robust.

  22. 3He effect in solid 4He Even though supersolid fractionis sensitive to the geometry and thermal history, The effect of 3He on the onset temperature is robust.

  23. 3He effect in solid 4He The effect of 3He on the onset temperature is robust.

  24. 10 and 30ppm 3He in solid 4He Effect of 3He on supersolid transition

  25. Channel width=0.5cm (ID=1.27cm OD=1.77cm) 3.25cm Isotopically-pure 4He? 3.0cm Tc is too low? or Supersolid fraction is too small?

  26. Isotopically-pure* 4He (*X3~1ppb) This work is done in the B/T facility of the high magnetic field lab. Dr. Xia (University of Florida) 1.0cm Torsion cell Total mass loading due to solid helium He-empty=3939ns Shift in the period =1ns Supersolid fraction ~1ns/3939ns ~0.025% Torsional oscillator f0= 1298Hz, Q~1x106

  27. Isotopically-pure* 4He (*X3<1ppb) 1ppb Samples grown by CP or CT NCRIF0 Be-Cu TO ( 0.3%) Ag TO (0.03%)

  28. Isotopically-pure* 4He (*X3<1ppb) 1ppb Samples grown by CP or CT NCRIF0 Be-Cu TO ( 0.3%) Ag TO (0.03%)

  29. Isotopically-pure* 4He (*X3<1ppb) This work is done in the B/T facility of the high magnetic field lab. Dr. Xia (University of Florida) No extra temperature dependence down to 1mK.

  30. Isotopically-pure* 4He (*X3<1ppb) This work is done in the B/T facility of the high magnetic field lab. Dr. Xia (University of Florida) No extra temperature dependence down to 1mK.

  31. Mixtures of X3=15ppb The effect of 3He impurity Tc~110mK Supersolid fraction ~0.11%

  32. Effect of 3He Addition of 3He enhances Tc NCRI marches up to higher temperature with increasing 3He concentration.

  33. Effect of 3He Addition of 3He enhances Tc NCRI marches up to higher temperature with increasing 3He concentration.

  34. Temperature dependence

  35. Temperature dependence

  36. Effect of 3He Phase separation ? regular solution theory

  37. Common defect in crystals  dislocation line Ultrasound measurements: Dislocation density in poor crystals ~ 109 per cm2 (constant volume1) Dislocation density in good crystals ~ 105 - 107 per cm2 (constant pressure2 or temperature3 above ~ 0.5K) Dislocation density in best crystals ~ 0 to 100 (constant temperature4 growth below ~ 0.2K) Dislocation 1. S.H. Castles & E.D. Adams, JLTP 19, 397 (1975). 2. I. Iwasa, K. Araki & H. Suzuki, J. Phys. Soc. Jap. 46, 1119 (1979). 3. V.L. Tsymbalenko, Low Temp. Phys. 21, 129 (1995). 4. J.P. Ruutu, P.J. Hakonen, A.V. Babkin, A.Ya. Parshin & G. Tvalashvili, JLTP 112, 117 (1998).

  38. Dislocation • Dislocation density, L = 5 ~ 1010 cm-2 • Solid helium grown by a constant volume • method; =105 to 107 cm-2 • Dislocations intersect on a characteristic length scale of LN • ( if ~105 to107 cm-2) • LN20.19  LN~ 1 to 10mm • Dislocations can also be pinned by 3He impurities • LC~ Distance between 3He atoms Lc LN

  39. Dislocation slip Influence of an increasing external stress is shown in the fig. For small stress dislocation is pinned down by the impurity particles(A). Then for small stress the loops starts to deflects. At the break-away stress a large increase of the dislocation strain appears.

  40. Torsion rod Torsion cell Detection Drive Torsional oscillator at 10 mm/s: s ~ 0.001 Pa Torsion cell In our torsional oscillator measurements , we gently oscillate a solid helium sample contained in a torsional cell. (stress applied < 0.1 dyne/cm~ 10-3Pa)

  41. 3He and dislocation • Actual 3He concentration on dislocation line is thermally activated *Typical binding energy is very small , W0, is 0.3K to 0.7K • Pinning length due to 3He impurity

  42. 3He-dislocations interaction Line was drawn by considering W0=0.75K and average L3He pinning length~ 0.15m. Average length LNetwork ~ 0.15 mm for L ~ 109cm-2 (CV) Smaller lengths are expected for larger dislocation densities  cross-over from network pinning to 3He pinning

  43. 3He-dislocations interaction Much smaller lengths are expected in Vycor glass ( most of all dislocations are pinned) Why no difference in Vycor?

  44. Channel width=0.5cm (ID=1.27cm OD=1.77cm) 3.25cm Stiffening of solid helium in the cell? 3.0cm Wall thickness of some cells very thick  It is highly unlikely that NCRI is due to stiffening

  45. Effect of 3He Tc or onset temperature and supersolid fraction of superflow show strong dependence on concentration of 3He.

  46. Summary • Dramatic effect of 3He impurities on supersolid 4He. The addition of 3He impurity broadens transition and enhances the onset temperature. • Not solely due to 3He impurities • Not 3He-4He phase separation of a solid mixture • The effect may be related with dislocation pinning by 3He. After dislocation motion pinned by 3He impurities supersolid phase appears • Pinning of dislocation increases shear modulus of solid helium?

More Related