Ultrasonic investigations of two order-parameter collective modes in superfluid /sup 3/He-B

Thesis/Dissertation · Thu Dec 31 23:00:00 EST 1981

OSTI ID:6846014

Mast, D B

Simultaneous measurements of the changes in the attenuation, group velocity and phase velocity of sound at the collective mode/zero sound mode crossings were made with pulsed transmission ultrasonic techniques. Zero sound at discrete frequencies between 12 and 133 MHz was used to excite these collective modes at temperatures between 0.5 mK and the superfluid's transition temperature. These measurements were made in zero applied magnetic field for a series of /sup 3/He pressures between 11.7 and 15.5 bar. Measurements of the relative change in the superfluid's acoustic impedance were also made at these mode crossings for /sup 3/He pressures between 1.64 and 4.88 bar. These measurements were made with a cw impedance technique (at sound frequencies of 12, 36, and 60 MHz) with and without magnetic fields applied to the sound propagation region. From these experiments the magnitude and temperature dependence of the collective mode frequencies and coupling strengths to zero sound were determined. The Zeeman splitting of only the real squashing mode in the applied magnetic fields was observed. The values of these frequencies are consistent with values calculated from a theory that incorporates Fermi liquid parameters F/sub l//sup s,a/(lless than or equal to2), pairing potentials v/sub l/(l = 1,3) and strong-coupling modifications to the weak-coupling BCS gap function. The low temperature value of the squashing mode coupling constant is in good agreement with the theoretically predicted value. A value for the particle-hole asymmetry in /sup 3/He-B (determined from the coupling constant of the real squashing mode) is consistent with existing theory. The observed Zeeman splitting of the real squashing mode is consistent with the existing theory for the bulk liquid.

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• OSTI ID: 6846014
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DATA
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HELIUM 3
HELIUM 3 B
HELIUM ISOTOPES
IMPEDANCE
INFORMATION
ISOTOPES
LAMBDA POINT
LIGHT NUCLEI
MATHEMATICAL MODELS
NUCLEI
NUMERICAL DATA
OSCILLATION MODES
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
ZEEMAN EFFECT
ZERO SOUND