measurements of the leggett frequency in 3 he-b in aerogel v.v.dmitriev, v.v. zavjalov, d.ye. zmeev,...
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Measurements of the Leggett Frequency in 3He-B in Aerogel
V.V.Dmitriev, V.V. Zavjalov, D.Ye. Zmeev, N.Mulders+
University of Delaware, USA
Kapitza Institute, Moscow
solid 3He
normalphase
«A»
«B»
T (mK)
P (
bar)
35004602/
1100140
5.255.19
H
andP bar
Oe
kHz
Conditions of our experiments:
L
0 0
0
2
),cos41(154
L
BL
104)4/1arccos(, 0HL
Brinkman-Smith mode: HM
“Usual” bulk 3He-B:
Low excitation CW NMR in 3He-B:the form of the line is defined by distribution of vector n
max
0
L
B
L
B
52
sin2
2
max
22
SnRL ˆ),ˆ(ˆ n
Low excitation CW NMR in 3He-B:the form of the line is defined by distribution of vector
max
0
L
B
L
B
52
sin2
2
max
22
SnRL ˆ),ˆ(ˆ L̂
L̂
1 см
Experimental chamber No 1
H
H
)5.25(76.0 barTT bulkcca
barP
TT
OeH
ca
5.25
76.0
284
Low excitation CW NMR lines in 3He-B in aerogel in different cells for the same conditions
L
0 0
0
2
),cos41(154
L
BL
104)4/1arccos(, 0HL
Brinkman-Smith mode: HM
“Usual” bulk 3He-B:
(degrees)
ca
ca
TTOeH
TTOeH
83.0,1010
78.0,285
Initial frequency of the FIDS versus the tipping angle
H
H
z
zw
z2
z1
)(0
wRF zgH
zHHH
z2
H0
z1
M
HHgRF
0/
z
The HPD in nonlinear CW NMR
HH
z
TT
cmOeH
OeH
RF
ca
0
0
/
67.0
/0.1
284
0.01 Oe
0.005 Oe
0.002 Oe
Sig
na
l am
plit
ude
z (mm)
Oe
The HPD in nonlinear CW NMR
Spatially homogeneous modes of oscillations of the HPD
Rotating frame:
L8
32
222BL
H
x
yh
M
)3/81(154
22
22
LB
B
L
h
Experimental cell for studies of low frequency HPD oscillations
OeH
Oeh
OeH
03.0~
01.0~
2840
)5.25(81.0 barTT bulkcca
HPD formation in cell with aerogel
H-H0 (Oe)
Ab
sorp
tion
& d
ispe
rsio
n
0
H0=284 Oe, С H=0.2 Oe/cm
Spatially homogeneous modes of oscillations of the HPD
Rotating frame:
L8
32
222BL
H
x
yh
M
)3/81(154
22
22
LB
B
L
h
time (ms)
Lock
-in o
utpu
t
Bulk 3He-B
Oscillations frequency vs RF-field amplitudeBulk 3He-B.
(Hz2
)
h (mOe)
barP
TT
OeH
c
5.19
606.0
2840
B-like phase of 3He in aerogel
time (ms)
Lock
-in o
utpu
t
Leggett frequency in bulk 3He-B ( ) and in 3He-B in aerogel ( )(solid line from: P.J.Hakonen et.al., JLTP, 76, 225 (1989))
barP 5.19
0.6 0.7 0.8 0.9 1.00
20
40
60
80
100
120
140
160
180
B/2
(k
Hz)
T/Tc, T/Tca
0.6 0.7 0.8 0.9 1.00
20
40
60
80
100
120
140
160
180
200
220
B/2
(k
Hz)
T/Tc, T/Tca
barP 5.25
Leggett frequency in 3He in aerogel ( ) for 25.5 bars(solid line is for bulk 3He-B : P.J.Hakonen et.al., JLTP, 76, 225 (1989))
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
-1 0 1 2 30.0
0.2
0.4
0.6
0.8
0.6 0.7 0.8 0.9 1.00
20
40
60
80
100
120
140
160
180
200
220
B/2
(k
Hz)
T/Tc, T/Tca
barP 5.25
Leggett frequency in 3He in aerogel ( ) for 25.5 bars(solid line is for bulk 3He-B : P.J.Hakonen et.al., JLTP, 76, 225 (1989))
barP
TT
OeH
ca
5.25
76.0
284
-1 0 1 2 30.0
0.1
0.2
)(2/ kHz
abso
rptio
n (
arb
. un
its)
barP
TT
OeH
ca
5.25
76.0
532
Conclusions:
- New mode of the HPD oscillations has been found. It has allowed to measure the Leggett frequency in 3He-B in aerogel
- Orienting influence of the boundary “aerogel - bulk 3He” on the texture of and n is different from that known for the the boundary “bulk 3He - wall”
L̂
Conclusions:
- New mode of the HPD oscillations has been found. It has allowed to measure the Leggett frequency in 3He-B in aerogel
- Orienting influence of the boundary “aerogel - bulk 3He” on the texture of and n is different from that known for the the boundary “bulk 3He - wall”
L̂
is parallel to the boundary “aerogel-bulk 3He”?L̂
barPOeH 5.25,1010
z (mm)
Ab
sorp
tion
an
d d
isp
ersi
on
Oeh
TT
cmOeH
OeH
ca
01.0
66.0
/94.0
2840
The HPD in the cell partially filled with aerogel
am
plit
ude
mmL
TT
cmOeH
OeH
HPD
ca
7.4
66.0
/94.0
2840
FIDS from the HPD in the cell partially filled with aerogel
time (s)
0.6 0.7 0.8 0.9 1.00
20
40
60
80
100
120
140
160
180
T/Tc, T/Tca
B/2
(k
Hz)
filling factor
Fre
que
ncy
(Hz)
)bulk(5.0)aero( effeff )s(T/T1/5.0)bulk( ceff )s/cm(T/T11300)bulk(c c|| )bulk(c5.0)aero(c ||||
)bulk(41.0)aero( BB )kHz(T/T13302/)bulk( cB
m1 m2
k1 k2
k0
Frequency of oscillations vs amount of aerogel(results of computer simulations of Leggett equations)
CAC T75.0T6.0T cell length=1.8 mmmOe6.7h
Free induction decay signal (FIDS)recorded by digital oscilloscope
Time (ms)
FID
S a
mpl
itude
time (ms)
barP
TT
OeH
ca
5.25
83.0
1010
Pure 3He + aerogel:2 solid monolayers of 3He on surface of aerogel strands:
mKTc
5.0~θθ
χ s
s
ss
MMMM
4He replaces 3He atoms at surface:
0χ s NMR signal is determined only by liquid 3He
time (s)
am
plit
ude
mmL
TT
cmOeH
OeH
HPD
ca
9.4
67.0
/0.1
2840
FIDS from the HPD with initial length of 4.9 mm
Sig
na
l am
plit
ude
Oe
Oe
z (mm)
caTT
cmOeH
OeH
65.0
/94.0
2840