QFS2016 Book of Abstracts

Abstracts

P4.2 Spontaneous annihilation of topological defects in 3 He-A near T c Kasai Jun(1), Okamoto Yohei(1), Nishioka Keishi(1), Takagi Takeo(2), and Sasaki Yutaka(1) 1) Dept. of Physics, Kyoto University, Kyoto, Japan. 2) Dept. of Applied Physics, University of Fukui, Fukui, Japan. 3) LTM Center, Kyoto University, Kyoto, Japan We have succeeded in stabilizing a number of textural domain walls inside a single 100 micrometer thickness slab of superfluid 3 He-A. A real space distribution of those topological defects is observed by our MRI measurements. The locations and the shapes of topological defects remain the same as far as they are kept quietly in a deep A phase. However, we found that the topological defects move and annihilate spontaneously at temperature very near Tc. During the annealing process there appears a spontaneous change in NMR spectra, which can be interpreted as spontaneous heat generation. However the relation between annihilation and heat generation is not clear at this moment. P4.3 Demagnetisation of Solid 3 He on Aerogel to Study Quasiparticle-Free Superfluid Bradley D. I.(1), Fisher S. N.(1), Guenault A. M.(1), Haley R. P.(1), Halperin W. P.(2), Pickett G. R.(1), Shen Y.(2), Tsepelin V.(1), Vonka J.(1), Zimmerman A.(2), and Zmeev D. E.(1) 1) Department of Physics, Lancaster University, Lancaster LA1 4YB, UK 2) Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA We describe an experimental setup to study both solid and superfluid 3 He at ultra-low temperatures. A layer of solid 3 He formed on the surface of a large aerogel sample submersed in superfluid 3 He will be cooled down to below 100 µ K in a double nuclear demagnetisation process. NMR on the solid 3 He will be used to search for the possible magnetic phase transition. Additionally, within the aerogel sample there is a cavity to create superfluid completely insulated from all parasitic heat flows. Here we intend to study the Bose-Einstein condensate of magnons in the state virtually free of quasiparticle excitations. In this contribution we report the progress made in these experiments.

116