NMR studies of superfluid ³He in low density silica aerogels

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• 作者：Baumgardner ; J.E. ; Polukhina ; L.V. ; Lee ; Y. ; Poco ; J.F. ; Hrubesh ; L.W. ; Osheroff ; D.D.
• 关键词：67.57.Lm ; 67.57.Pg ; Superfluid ³He ; Aerogel ; Unconventional BCS states ; Impurity depairing
• 刊名：Physica B
• 出版年：2003
• 出版时间：May, 2003
• 年：2003
• 卷：329-333
• 期：Part 1
• 页码：292-295
• 全文大小：176 K

文摘

Continuous wave NMR studies of superfluid ³He in 99.4 % , 98.7 % and 98.3 % porosity silica aerogels show similar phase diagrams, with an equal spin pairing (ESP) A-like state stable near T_c,a, and a B-like phase stable at lower temperatures. On cooling through T_c,a, the sample magnetization and frequency shift show substantial supercooling of the A-like phase, with discontinuous changes to B-like behavior seen at about 0.64T_c,b (bulk) for all samples. On warming, both the frequency shift and magnetization change continuously as the sample enters an ESP state. This suggests that this phase transition is broadened by pinning of the A–B interface on density fluctuations in the aerogel, even very close to T_c,a.