QFS 2016 Book of Abstracts

Abstracts

I2.1 Non-isothermal Physico-Chemical Processes in Superfluid Helium Haley R. P. Lancaster University Coherent condensates appear as emergent phenomena in many systems, sharing the characteristic feature of an energy gap separating the lowest excitations from the condensate ground state. An object moving with high enough velocity that the excitation spectrum becomes gapless can create excitations at no energy cost and initiate the breakdown of the condensate. This limit is the well-known Landau velocity. For the neutral Fermionic superfluid 3 He-B in the T=0 limit, flow around an oscillating body displays a very clear critical velocity for the onset of dissipation. However, to our considerable surprise, we have found that for uniform linear motion there is no discontinuity whatsoever in the dissipation as the Landau critical velocity is passed and exceeded. I2.2 Visualizing Textural Domain Walls in Superfluid 3 He by Magnetic Resonance Imaging Kasai Jun(1), Okamoto Yohei(1), Nishioka Keishi(1),Takagi Takeo(2), and Sasaki Yutaka(1,3) A real space image of textural domain walls inside a single 100 micrometer thickness slab of superfluid 3 He-A was MRI-imaged. Straight lines, which appeared in between large domains of uniform textures, were textural domain walls (solitons) with particularly important feature. The observed NMR properties suggest that the domain wall has almost dipole-locked soliton structure inside the wall, which connects two regions of uniform d = l texture with different chirality, namely d , l and – d , − l . This soliton is accompanied with two surface chiral domain walls located back to back on both side of the slab surface. The surface chiral domain walls anchor the dipole-locked soliton in its place. 1) Dept. of Physics, Kyoto University, Kyoto, JAPAN. 2) Dept. of Applied Physics, Univ. of Fukui, Fukui, JAPAN. 3) LTM Center, Kyoto University, Kyoto, JAPAN.

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