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Session I10 - DFD: $^(3)He,$^(4)He and $^(3)He$-$^(4)He Mixtures
MIXED session, Thursday morning, April 20, 8:00
Room 4, Renaissance Hotel
We report measurements at various pressures of the magnetization and magnetic resonance frequency of ^3 He in 98% porous aerogel using pulsed NMR techniques. Our results provide evidence for superfluidity but with a suppressed transition temperature, T_p, relative to the bulk superfluid temperature, T_c . Above T_p the resonance frequency is constant. Similar to the A-phase, below T_p the resonance frequency is observed to rise continuously with decreasing temperature. T_p is 68 % to 85 % of T_c with the greater suppression occurring at the lower pressures. There are no observable discontinuities in the magnetization or its slope at T=T_p, and so it is likely that the order parameter is an equal spin pairing state. The tipping angle dependence of the resonance frequency is neither A-phase nor B-phase like. The resonance frequency of 3.6 MHz has been studied, and work at other fields is underway.
This work is supported by the National Science Foundation through grants DMR-9314025 and DMR-9311918.
Previous abstract
Next abstract
Session I10 - DFD: $^(3)He,$^(4)He and $^(3)He$-$^(4)He Mixtures
MIXED session, Thursday morning, April 20, 8:00
Room 4, Renaissance Hotel
We have made high resolution magnetic resonance measurements of the ^3 He normal Fermi liquid Larmor frequency. At high temperatures, near the Larmor frequency is temperature independent. At lower temperatures we observe a negative shift from this value that is approximately proportional to the inverse temperature, increasing to a maximum shift of order 1/10 ^6 at the superfluid transition temperature ( \approx 1 mK ). The dependence of this shift on pressure (over the range 0.3 to 28.8 bar) and magnetic field, ( 0.04 and 0.12 T) is discussed. This work is supported by the National Science Foundation through grants DMR-9314025 and DMR-9311918.