Longitudinal magnetic resonance (NMR) in the A1 phase of superfluid 3He

The Ginzburg-Landau theory is used to calculate the distortion of the conventional A1- and A2-phase order parameters A/sub μ//sub i/ arising from the dipole energy. The nine perturbations deltaA/sub μ//sub i/ are of order g/sub D//eta'Hroughly-equal10-3/H[kG] for μ = x and y and of order g/sub D//g/sub z/H2 for μ = z. They depend sensitively on the stron coupling corrections. The resulting changes of the up-spin and down-spin pairing amplitudes as functions of T are strongly peaked at T/sub A/2. The deltaA/sub μ//sub i/ tend to modify the conventional A1-phase state into a polar, J/sub z/ = +1, state as T is increased toward T/sub A/1. The perturbations deltaA/sub μ//sub i/ give rise to small changes of order g/sub D/(g/sub D//eta'H) of all components of Leggett's dipole frequency tensor Ω/sub i/j2. The effect on the transverse NMR shift is negligibly small. however, in the A1 phase a finite longitudinal NMR frequency ν/sub L/ is obtained. The curve of ν/sub L/ versus T drops steeply close to T/sub A/2, and at T/sub A/2 an inflection point occurs where ν/sub L/roughly-equal3 kHz. For T>T/sub c/, ν/sub L/ goes almost linearly to zero at T/sub A/1. Observation of a finite ν/sub L/ would be a proof that the A1 phase is not a pure condensate of a single equal-spin-pairing (ESP) component: it contains a small amount of the opposite ESP component