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Gap parameters and collective modes for3He-B in the presence of a strong magnetic field

✍ Scribed by L. Tewordt; N. Schopohl


Publisher
Springer US
Year
1979
Tongue
English
Weight
911 KB
Volume
37
Category
Article
ISSN
0022-2291

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✦ Synopsis


First we determine the 4 β€’ matrix" Green's function for a p-wave pairing superfluid in a magnetic field where the order parameter is given by a real 3 x 3 matrix. For the B phase we take an order parameter which is equal to A i times a 3 β€’ 3 matrix, yielding a rotation of angle 0 about the z-axis and a dilatation A 2/A I along the z-axis. Then the self-consistency equation for the 4 β€’ 4 matrix self-energy reduces to three equations for AI, Az, and cos O, and a fourth equation for the renormalized Larmor frequency. We find that, for increasing field, AI increases and Zlz decreases with respect to the zero-field gap zloo. Above a (temperature-dependent) critical field we find A2 = 0 and 0 = 90 ~ corresponding to the planar state of lowest dipole energy. The correlation functions for the order parameter collective modes are calculated with the help of a previous theory. The results can be expressed in terms of six universal functions describing internal magnetization and virtual excitations of pairs of quasiparticles with all spin orientations. The complete set of eigenfrequencies as functions of the field is calculated for T = 0 and q = O. The longitudinal NMR frequency is found to be almost independent of the field. We find a splitting of the pair-vibration frequencies (8/5) 1/2 A oo and (12/5) I/2A oo which is linear in the field. This splitting is caused by fluctuations involving the spin-singlet component of the anomalous propagator. The splitting of the pair-vibration frequency (12/5) 1/2,.4oo (of the order 6H MHz, H in k G ) should be observable by sound absorption experirhents in strong magnetic fields.

which is determined from the generalized Gorkov equation for spin-triplet 9 9 2 ..... p-wave pamng. In this equatmn the gap matrix ~s taken in the usual general 9 A ~ A.


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