Rayleigh sound wave propagation on a gallium single crystal in a liquid He3 bath

G. Bellessa

To cite this version:

G. Bellessa. Rayleigh sound wave propagation on a gallium single crystal in a liquid He3 bath. Journal de Physique Lettres, Edp sciences, 1975, 36 (5), pp.137-139. ꢀ10.1051/jphyslet:01975003605013700ꢀ. ꢀjpa-00231172ꢀ

HAL Id: jpa-00231172 https://hal.archives-ouvertes.fr/jpa-00231172

Submitted on 1 Jan 1975

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L-137

RAYLEIGH

GALLIUM

SINGLE

SOUND

WAVE

CRYSTAL IN

PROPAGATION

A

ON

A

He3 BATH

LIQUID

G. BELLESSA

Laboratoire de

des Solides

91405

Physique

Centre

(*)

Université

France

Paris-Sud,

d’Orsay,

Orsay,

Résumé.

un monocristal de

Nous décrivons

de

l’observation de la

d’ondes

sur

propagation

d’études sont

élastiques

Rayleigh

entre 40 MHz et 120 MHzet

Les

gallium.

d’étude la

fréquences

basse est K. La

comprises

la

et

vitesse

l’atténuation sont étudiées

le bain

à

des

0,4

température

tures différentes. L’atténuation des ondes de

plus

tempéraà des tem-

d’He3 est aussi étudiée

Rayleigh par

et des

différentes.

pératures

fréquences

Abstract.

We

the

report

observation of the

to 120 MHzand

sound wave

on

a

Rayleigh

propagation

gallium

and the

the He3

at

down to 0.4 K. The

single crystal

frequencies up

temperatures

velocity

by

attenuation are studied

at different

The

attenuation of

waves

temperatures.

and

Rayleigh bath is also

studied at different

temperatures

frequencies.

Elastic surface waves have been

studied

quartz

combs are

comb teeth are 20

other of 40

on the ZnS film

The

extensively

and lithium

evaporated

1).

(Fig.

on

wide and

are distant from each

materials,

piezoelectric

mainly

p.

niobate

waves on

There are ^also some

films

studies of

Each comb consists

of teeth and is

40

[1].

Rayleigh

on

~.

a

distant from its

0.5

6

mm.

A

RF

piezoelectric

evaporated

glass

neighbour by

pulse

substrate

The effects of thin

metallic films eva-

is

between ^one comb

[2].

on

(about

duration)

gas

applied

a

substrate have been

and the

metallic

is

porated

studied

piezoelectric

sample (the

sample

grounded).

and the effects of the

electrons on ^the

[3, 4]

of

waves have been observed

propagation

Rayleigh

the

(mainly

transition).

normal-superconducting

However the

of these effects are

small,

magnitude

because the thickness of the

much smaller than the

films are

evaporated

In this

wave

Rayleigh wavelength.

ofthe

we

the observation

a

letter,

report

on

Rayleigh

We

single crystal.

the attenuation

propagation

gallium

report

varia-

some

results about

preliminary

transition and

tion in the

normal-superconducting

waves

He3.

aboutthe attenuationof

Rayleigh

byliquid

The

is

single crystal

Experimental technique.

made with

in

The

a

mold

which

plastic

single crystal

very pure gallium

has two

machined and

faces

is not

wave

FIG. 1.

for

wave

the

polished

[5].

Experimental

arrangement

are the

Rayleigh

gene-

ration. The

c

axis

axis ofthe Gallium

a, b,

surfaces for the

crystallographic

good

Rayleigh

with

the

usual notations.

crystal

are obtained

this method. The

propagation

directly by

flat surfaces of the

^are normal to the

b

gallium crystal

film

ZnS

of

is

axis

and

onto the

a

(Fig. 1)

evaporated (about

A

the

wave

is

on the metal surface if

Rayleigh

generated

This

film

6

000

A)

crystal.

piezoelectric

of

the RF

is

the wave-

such that

frequency

pulse

acts as an electro-mechanical transducer. Twometallic

of the

wave

the teeth

length

Rayleigh

equals

propagates

reaches the second comb

spacing.
The acoustic surface

wave

normal to the

comb teeth and

is

Laboratoire ^associe au C.N.R.S.

(*)

(which

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyslet:01975003605013700

L-138

well

to the first

after

a

certain

time. At

TABLE

I

one)

is observed on

parallel

^an RF_pulse

this time

the

second comb.

in

at

waves velocities

105

Rayleigh

(in

cm/s)

gallium

no reflexion of the

Weobserve

combs. So

case of bulk acoustic

on ^the

pulse

The

b

axis

is normal

different

(in Kelvin).

temperatures

and the

sound

there are no ^successive

and it is not

echoes

in the

(as

to the

The

is

the

c

a.~is.

surface

propagation

along

wave

to make an

waves)

possible

velocities

the bulk

for

propagation

measurement of the attenuation.

absolute

In

order to

three

evaporate

the

b

axis are taken

K. R.

and

along

from

Lyall

do

it

would be

to

this,

necessary

J. F. Cochran

[6].

metallic combs on ^the

2

shows the

crystal. Figure

that we ^observe on the

second comb

delayed pulse

after

and detection. The first saturated

to the

amplification

excitation of the

waves

on

pulse corresponds

pulsed

emitter comb. We have observed

at 40 MHz

Rayleigh

80 MHz and

gallium

(fundamental),

harmonics).

120 MHz_(2nd and 3rd

We have also

the

in

K

a

field

put

sample

At 0.4

magnetic

to the

is

there

a

(normal

surface).

sharp

super-

In the normal

in the attenuation in the

transition

of

the

change

vicinity

conducting

(around 60 Oe).

2

it

the attenuation increases

to

kOe.

Then

state,

up

remains

constant

to 10 kOe. The total

roughly

up

K

MHz

and 80

is

variation of the attenuation at 0.4

found to be :

Attenuation of

waves

He~.

rayleigh

by liquid

of

The main mechanism of

absorption

Rayleigh

compres-

waves

ambient

media is the emission of

by

^sional waves ⁱⁿ

the fluid

the

during

propagation [1].

This

for the attenuation :

process

gives

FIG. 2.

to the the

Recorder

wave

of

the

The

first saturated

a)

tracing

delayed

pulse corresponding

train.

to

Rayleigh

pulse corresponds

excitation of the emitter comb.

Recorder

• of
• pulsed

b)

versus the

tracing

the

variation

level. Out

delayed

sample

changed by

pulse amplitude

liquid

liquid

at 1.2 K.

where

the

is the fluid

the

the

in

sound

pp

density, VF

of the

velocity

the

wave.

means

surface

out of the He3 bath. The

level is

fluid,

solid,

p

density

VR

Rayleigh

He3

and ÅR

liquefying

gaz

slowly

and the

of the

a

velocity

wavelength

we start from

surface out of

of the

wave

Experimentally,

sample

and attenuation

to measure the

measurements.

wave

There

Velocity

are two

the He3 bath and we record the

amplitude

Rayleigh

liquid

ways

Rayleigh

velocity.

to the

delayed pulse corresponding

,

Thefirst one is to measure the transit time ofthe

between the two combs. The second is to

pulse.

train

Wethen

and werecord

as soon as

the

level in the

(Fig. 2).

change

• the
• adjust

a

decrease ofthe

cryostat

delayed pulse

of the RF

in order to obtain the

on the receiver

frequency

largest amplitude

pulse

of the

He3 covers the

recorder

the attenuation does not

amplitude

liquid

sample

delayed pulse

surface.

2

shows such

a

As

tracing.

Figure

comb. This last method is the most sensitive because

can be seen on the

curve,

to its final value. We shall

the

of the comb’ is

ofthe numberofteeth andour combs

to the

selectivity

proportional

consider this

fall

directly

square

are

(40 teeth)

varia-

In

later. Wehave measured the attenuation

point

I

Table

the results of our

selective

[1 ].

gives

very

different

and

tion for

frequencies.

temperatures

measurements at different

and the bulk

temperatures

comparison

measure the attenuation

the ratio of the

we do not

in the two

to the

order to

take

variation,

wave velocities for

As we have written

from ref.

(taken

[6]).

pulse heights

simply

we cannot

measure the

above,

errors

This method can introduce

ofthe

cases.

owing

absolute attenuation but wecan measure ^the variation

Weavoid this

non-linearity

amplifiers.

possible

ofthe attenuationversus

The

attenuation

4.2

and

temperature.

the RF

generator amplitude

difficulty, by changing

is found to be

constant between

K

roughly

in

to obtain the same

We then take the ratio

the two

corresponding

Our results are

in order

pulse height

1.1

K_{(superconducting}

transition

Below 1.1

K

of Ga).

sensitive to the

of the

cases.

is

the attenuation

very

temperature.

of the

values

generator amplitude.

have found for

We

the variation of the attenuation

in Table II. There is no measurement at

and 1.2 K because the attenuation of

reported

of surface waves at 80 MHz :

,

120 MHz

waves ⁱⁿ

is

above the

11

0.5

K) -

K)

~(0.4

dB/cm .

gallium

very large

Rayleigh

o~(1.2

L-139

TABLE II

In

variation

conclusion let us

consider the

covers the

attenuation

surface

.

as

the

Measured values

waves ⁱⁿ

the attenuation

just

In

maximum

liquid

sample

of

(in

dB/cm)

(leal

of

^this case the

attenuation curve has successi-

He3.

is

(Fig. 2).

the

Rayleigh

gallium by liquid

a

and

2

a

minimum before

its

calculated value

1.

At 0.4

K

Gallium

vely

reaching

obtained from

eq.

final value

the

minimum

corres-

is

T

is

the

wave.

F

and

the

(in Fig.

amplitude

superconducting.

temperature

to the

This

behaviour

attenuation

the

ponds

can be

maximum).

frequencyof

Rayleigh

into account the effect ofan

surface. The attenuation

explained by taking

helium film

the

on

sample

does

not consider

return

to

(1)

any

waves on ^the surface

process leading

of the emitted

eq.

compressional

helium

film

on the

a

there is

If,

sample.

sample,

to

it is then

instead ofa semi-infinite

media,

reflections.

necessary

the

consider such

wave ^radiates

Schematically

Rayleigh

a

wave

which is almost

compressional

transition

and

temperature

significant

it

has

the

superconducting

is

to Arc

normal to the surface

(the

angle

compressional

of the film and then returns

therefore

equal

notbeen

possible

to

obtain

a

value.

The

calculated

(leal is

The

wave is reflected

sin

40).

VF/VR

on ^the

calculated

values are

obtained from

value

eq. (1).

surface

sample

upper

toward the

smaller than

therefore seems there is

the

systematically

experi-

surface. There are

mental ones. ^It

attenuation

the

wave.

wave and the

If the interferences are

interferences between

Rayleigh

mechanism other than that due to the

emission of

reflected

compressional

waves

the

It is

compressional

during

to consider in the

propagation.

if

d

destructive i.e.

2 d

is

+

(2 n

1)

(where

in the

~,F/2

not

case the

necessary

present

from frictional

the film thickness

there is an attenuation maximum. There is ^also an

^and the

wavelength

fluid),

attenuation

losses

process arising

[1].

This mechanism

x

indeed

a

attenuation

gives

negligible

minimum

if

attenuation

2 d ^~

Thus

the maxi-

~p.

MHz. At 0.4

at 80

K

to

5

10-3

equal

(Ga

dB/cm

mum^and the minimum of the attenuation in

2

figure

is then

the

attenuation

superconducting),

by

would

and

to

a

thickness of

film

correspond

0.5 ~

~,F/4

He3 versus

does not deviate

liquid

frequency

appre-

if

the

/!.F/2

1 ~

respectively. Experimentally,

from

a

linear law in

with

ciably

agreement

longer proportional

what weare

(1).

to

eq.

film thickness was ^well defined there would

be

absorp-

At 1.2

K

the attenuation is no

tion resonances for

resonances would be

thicknesses and these

In our case the film

many

very sharp.

the

here

is,

frequency. Perhaps,

beginning,

surface wave ^attenuation

observing

at its

the effect of the electrons on the

thickness is

not well defined and we ^observe

resonance.

probably

helium.

This

by liquid

Kapitza

a

only

very damped

in the

effect is involved

resistance

pro-

Theauthor is indebted to L.

Dumoulinand M. Boix

for useful

advices about the

and to J. Joffrin for

blem

and has been observed in

[7]

gallium [8]. Expe-

necessary

riments at

date this

are

to eluci-

frequencies

evaporation

fruitful

discussion.

higher

techniques

a

interesting point.

References

K. and

Mason

edited

France S. A. for the

of

DRANSFELD,

SALZMANN, E.,

Acoustics,

1970,

J.

[1]

[2]

Physical

by

supply

very pure gallium.

49

P.

_(Academic, New_York)

vol.

219.

K. R. and

COCHRAN,

J.

Can. J.

1076.

W.

7,

LYALL,

F.,

Teor. Fiz. 43

[6]

Phys.

(1971)

p.

44

A.

Zh.

1535

K. and

INABA, R., KAJIMURA,

MIKOSHIBA, N.,

[7] ANDREEV,

F.,

(1962)

(Sov. Phys.

Appl. Phys.

Eksp.

(1963) 1084).

F. J. and

JETP 16

2495.

(1973)

AKAO, F.,

409.

Rev.

Lett. 30A

WAGNER, F., KOLLARITS,

YAQUB, M.,

• [8]
• [3]

[4] [5]

Phys.

(1969)

Rev. B 7

Phys.

1117.

119.

Lett. 32

KRÄTZIG, E.,

(1973)

to P. DE LA

(1974)

Phys.

of Alusuisse

The author is indebted

BRETÈQUE