Barker BI, Lee Y, Polukhina L, Osheroff DD, Hrubesh LW, Poco JF
Department of Physics, Stanford University, Stanford, California 94305-4060, USA.
Phys Rev Lett. 2000 Sep 4;85(10):2148-51. doi: 10.1103/PhysRevLett.85.2148.
New NMR studies of 3He in high-porosity aerogel reveal a phase transition from an A-like to a B-like phase on cooling. The evidence includes frequency shift and magnetic susceptibility data, and similar behavior is found in two quite different aerogel samples. The A-like phase is stable only very near to T(c) but can be supercooled to below 0.8T(c). This behavior has been seen clearly at 32- and 24-bar pressures, and the presence of negative frequency shifts suggests that an A-like phase exists near T(c) at pressures as low as 12 bars in a magnetic field of 28.4 mT.
对高孔隙率气凝胶中³He的新核磁共振研究表明，冷却时会发生从类A相到类B相的相变。证据包括频移和磁化率数据，并且在两个截然不同的气凝胶样品中发现了类似行为。类A相仅在非常接近T(c)时稳定，但可以过冷至0.8T(c)以下。在32巴和24巴压力下已清楚观察到这种行为，负频移的存在表明在28.4毫特斯拉的磁场中，在低至12巴的压力下，类A相在T(c)附近存在。
