|Probing the Upper Limit of Non-classical Rotational Inertia in Solid Helium4 |
Physics and Astronomy
|John Reppy, Cornell University|
1:30 PM, Room 385E Serin Physics Lab
We study the effect of confinement on solid 4He's non-classical rotational inertia (NCRI) in a torsional oscillator by constraining it to narrow annular cells of various widths. The NCRI exhibits an observed maximum value of 20% for annuli of ~ 100 micro-m samples constrained to porous media or to larger geometries both have smaller NCRI,mostly below ~ 1%. In addition, we extend Kim and Chan's blocked annulus experiment  to solid samples with large supersolid fractions. Blocking the annulus suppresses the non-classical decoupling from 17.1% below the limit of our detection of 0.8%. This result demonstrates the nonlocal nature of the supersolid phenomena. At 20 mK, NCRI depends on velocity history  showing a closed hysteresis loop in different thin annular cells.
Leggett, A.J. Can a solid be "Superfluid"? Phys. Rev. Lett. 25, 1543(1970).
Kim, E. and Chan, M.H.W. Observation of superflow in solid helium. Science 305, 1941(2004).
Aoki, Y., Graves, J.C., and Kojima, H. Oscillation frequency dependence of nonclassical rotation inertia of solid He-4.
Phys. Rev. Lett. 99, 015301(2007).