Measurements of the Leggett Frequency in 3 He-B in Aerogel V.V.Dmitriev, V.V. Zavjalov, D.Ye. Zmeev, N.Mulders + University of Delaware, USA Kapitza Institute, Moscow

solid 3 He normal phase «A» «B» T (mK) P (bar) bar Oe kHz Conditions of our experiments:

 L 0  00   Brinkman-Smith mode: “Usual” bulk 3 He-B:

Low excitation CW NMR in 3 He-B: the form of the line is defined by distribution of vector n  max 0 n

Low excitation CW NMR in 3 He-B: the form of the line is defined by distribution of vector  max 0

1 см Experimental chamber No 1

Low excitation CW NMR lines in 3 He-B in aerogel in different cells for the same conditions

 L 0  00   Brinkman-Smith mode: “Usual” bulk 3 He-B:

 (degrees) Initial frequency of the FIDS versus the tipping angle

z zwzw z2z2 z1z1 z2z2 H0H0 z1z1 The HPD in nonlinear CW NMR

0.01 Oe Oe Oe Signal amplitude z (mm) Oe The HPD in nonlinear CW NMR

Spatially homogeneous modes of oscillations of the HPD Rotating frame: H x y h M

Experimental cell for studies of low frequency HPD oscillations

HPD formation in cell with aerogel H-H 0 (Oe) Absorption & dispersion 0 H 0 =284 Oe,  H=0.2 Oe/cm

Spatially homogeneous modes of oscillations of the HPD Rotating frame: H x y h M

time (ms) Lock-in output Bulk 3 He-B

Oscillations frequency vs RF-field amplitude Bulk 3 He-B.   (Hz 2 ) h (mOe)

B-like phase of 3 He in aerogel time (ms) Lock-in output

Leggett frequency in bulk 3 He-B ( ) and in 3 He-B in aerogel ( ) (solid line from: P.J.Hakonen et.al., JLTP, 76, 225 (1989))  B /2  (kHz) T/T c, T/T ca

 B /2  (kHz) T/T c, T/T ca Leggett frequency in 3 He in aerogel ( ) for 25.5 bars (solid line is for bulk 3 He-B : P.J.Hakonen et.al., JLTP, 76, 225 (1989))

 B /2  (kHz) T/T c, T/T ca Leggett frequency in 3 He in aerogel ( ) for 25.5 bars (solid line is for bulk 3 He-B : P.J.Hakonen et.al., JLTP, 76, 225 (1989))

absorption (arb. units)

Conclusions: - New mode of the HPD oscillations has been found. It has allowed to measure the Leggett frequency in 3 He-B in aerogel - Orienting influence of the boundary “aerogel - bulk 3 He” on the texture of and n is different from that known for the the boundary “bulk 3 He - wall”

Conclusions: - New mode of the HPD oscillations has been found. It has allowed to measure the Leggett frequency in 3 He-B in aerogel - Orienting influence of the boundary “aerogel - bulk 3 He” on the texture of and n is different from that known for the the boundary “bulk 3 He - wall” is parallel to the boundary “aerogel-bulk 3 He” ?

z (mm) Absorption and dispersion The HPD in the cell partially filled with aerogel

amplitude FIDS from the HPD in the cell partially filled with aerogel time (s)

T/T c, T/T ca  B /2  (kHz)

filling factor Frequency (Hz) m1m1 m2m2 k1k1 k2k2 k0k0 Frequency of oscillations vs amount of aerogel (results of computer simulations of Leggett equations) cell length=1.8 mm

Free induction decay signal (FIDS) recorded by digital oscilloscope Time (ms)

FIDS amplitude time (ms)

Pure 3 He + aerogel: 2 solid monolayers of 3 He on surface of aerogel strands: 4 He replaces 3 He atoms at surface: NMR signal is determined only by liquid 3 He

time (s) amplitude FIDS from the HPD with initial length of 4.9 mm

Signal amplitude Oe z (mm)