Observation of a New Resonance in the Collective-Mode Spectrum of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">He</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>3</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math></span>-<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math></span>

M. W. Meisel; B. S. Shivaram; Bimal K. Sarma; J. B. Ketterson; W. P. Halperin

doi:10.1103/PhysRevLett.50.361

Observation of a New Resonance in the Collective-Mode Spectrum of ${}^{3}{He}$ - $A$

M. W. Meisel, B. S. Shivaram, Bimal K. Sarma, J. B. Ketterson, and W. P. Halperin

Phys. Rev. Lett. 50, 361 – Published 31 January 1983

Abstract

A high-resolution acoustic impedance technique has been used to investigate the collective-mode spectrum of ${}^{3}{He}$ - $A$ near $T_{c}$ . A new collective mode of the order parameter has been observed. The temperature at which the new mode appears is frequency, pressure, and magnetic field independent. The observed temperature dependence is very close to the predicted behavior of the super-flapping mode in the weak-coupling limit of the Anderson-Brinkman-Morel energy gap.