Doubly quantized vorticity and other NMR experiments on rotating 3He superfluids

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Doctoral thesis (article-based)
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Date
2001-04-06
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Language
en
Pages
48, [75]
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Abstract
This doctoral thesis consists of experimental studies on rotating superfluid helium-3 at millikelvin temperatures. Superfluid 3He provides an example of ordered systems where quantum phenomena are visible on a macroscopic scale. The order parameter is described by a 3x3 complex matrix leading to different superfluid phases with different properties. The A and B phases support topologically different kinds of defects, most notably vortex lines. Vortex lines are most easily created and studied in uniform rotation. Because of quantum nature, the circulation around the vortices is quantized in units of κ0 = h/2m3. In superfluid 3He nuclear magnetic resonance (NMR) provides a means to distinguish between different types of vortices and count them one by one. During the course of this work the sensitivity of the NMR spectrometer was improved by an order of magnitude, which enabled the direct measurement of the circulation of a vortex in the A phase that carries two circulation quanta (2κ0). Up to now the circulation of the known quantized vortex types in other quantum fluids, which include superfluid 4He, superconductors, and Bose-Einstein -condensates, has been singly quantized. Other NMR experiments reported in the thesis are: (1) The first qualitative measurements of vortex annihilation in the A and B phases of 3He. These measurements tell the lowest rotation velocity that stabilizes an array of vortex lines with a given number of vortices, and how it depends on the type of the defect. (2) Studies of vortex arrays with both singly and doubly quantized A phase vortex lines coexisting in the experimental container. 3He-A provides a unique system in which this kind of arrangement can be done. (3) In order to improve the vortex detection sensitivity in the B phase even further, the response of different nonlinear spin precession modes to superfluid-normal fluid counterflow was studied. A new mode, where the orbital angular momentum is oriented transverse to the external magnetic field, was found.
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Keywords
quantum fluids, superfluid helium-3, quantized vortices, vortex arrays, vortex formation, vortex annihilation, nonlinear NMR, superfluid-superfluid interfaces, nuclear magnetic resonance, NMR spectrometer
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Parts
  • Y. Kondo, J. H. Koivuniemi, J. J. Ruohio, V. M. Ruutu, and M. Krusius, Optimization of high-Q low frequency NMR measurement, Czech. J. Phys., vol. 46-Suppl., pp. 2843-2844, 1996. [article1.pdf] © 1996 Czech. J. Phys. By permission.
  • Ü. Parts, V. V. Avilov, J. H. Koivuniemi, M. Krusius, J. J. Ruohio, and V. M. H. Ruutu, Vortex arrays of coexisting singly and doubly quantized vortex lines in 3He-A, Czech. J. Phys., vol. 46-Suppl., pp. 13-14, 1996. [article2.pdf] © 1996 Czech. J. Phys. By permission.
  • Ü. Parts, V. V. Avilov, N. B. Kopnin, M. Krusius, J. J. Ruohio, and V. M. H. Ruutu, Coexistence of single and double quantum vortex lines, Phys. Rev. B, vol. 62, pp. 5865-5876, Sept. 2000. [article3.pdf] © 2000 The American Physical Society. By permission.
  • V. M. Ruutu, J. J. Ruohio, M. Krusius, B. Plaçais, E. B. Sonin, E. V. Thuneberg, and Wen Xu, Annihilation of quantized vortex lines in rotating 3He-A, Czech. J. Phys., vol. 46-Suppl., pp. 9-10, 1996. [article4.pdf] © 1996 Czech. J. Phys. By permission.
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  • V. B. Eltsov, V. V. Dmitriev, M. Krusius, J. J. Ruohio, and G. E. Volovik, New modes of stable spin precession in superfluid 3He-B, J. Low Temp. Phys., vol. 113, pp. 645-650, Dec. 1998.
  • V. V. Dmitriev, V. B. Eltsov, M. Krusius, J. J. Ruohio, and G. E. Volovik, Superflow-stabilized nonlinear NMR in rotating 3He-B, Phys. Rev. B, vol. 59, pp. 165-168, Jan. 1999. [article8.pdf] © 1999 The American Physical Society. By permission.
  • R. Schanen, R. Blaauwgeers, V. B. Eltsov, M. Krusius, and J. J. Ruohio, NMR measurement of quantized vortex lines in rotating 3He-B, Physica B, vol. 284-288, pp. 254-255, July 2000. [article9.pdf] © 2000 Elsevier Science. By permission. ScienceDirect®
  • J. Kopu, R. Schanen, R. Blaauwgeers, V. B. Eltsov, M. Krusius, J. J. Ruohio, and E. V. Thuneberg, NMR line shape of rotating 3He-B at large counterflow velocity, J. Low Temp. Phys., vol. 120, pp. 213 -232, Aug. 2000.
  • R. Blaauwgeers, V. B. Eltsov, M. Krusius, J. J. Ruohio, R. Schanen, and G. E. Volovik, Double-quantum vortex in superfluid 3He-A, Nature, vol. 404, pp. 471-473, Mar. 2000.
  • R. Blaauwgeers, V. B. Eltsov, M. Krusius, J. J. Ruohio, and R. Schanen, NMR measurement of quantized vortex lines in rotating 3He-A, Physica B, vol. 284-288, pp. 250-251, July 2000. [article12.pdf] © 2000 Elsevier Science. By permission. ScienceDirect®
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https://urn.fi/urn:nbn:fi:tkk-002749