Rayleigh Sound Wave Propagation on a Gallium Single Crystal in a Liquid He3 Bath G

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 <a href="/goto?url=https://hal.archives-ouvertes.fr/jpa-00231172" target="_blank">https://hal.archives-ouvertes.fr/jpa-00231172 </a>Submitted on 1 Jan 1975 <ul style="display: flex;"><li style="flex:1">HAL is a multi-disciplinary open access </li><li style="flex:1">L’archive ouverte pluridisciplinaire HAL, est </li></ul>archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. L-137 RAYLEIGH GALLIUM SINGLE SOUND WAVE CRYSTAL IN PROPAGATION AON AHe3 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 àdes 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 aRayleigh 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 ~. adistant from its 0.5 6mm. ARF piezoelectric evaporated glass neighbour by pulse substrate The effects of thin metallic films eva- is between one comb [2]. on (about duration) gas applied asubstrate 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 aletter, 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 amold 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 caxis 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 bgallium crystal film ZnS of is axis and onto the a(Fig. 1) evaporated (about Athe wave is on the metal surface if Rayleigh generated This film 6000 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 <a href="/goto?url=http://www.edpsciences.org" target="_blank">EDP Sciences </a>and available at <a href="/goto?url=http://dx.doi.org/10.1051/jphyslet:01975003605013700" target="_blank">http://dx.doi.org/10.1051/jphyslet:01975003605013700 </a>L-138 well to the first after acertain time. At TABLE Ione) is observed on parallel an RFpulse 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 baxis 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 ca.~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 baxis are taken K. R. and along from Lyall do it would be to this, necessary J. F. Cochran [6]. metallic combs on the 2shows 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 Kafield 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). 2it the attenuation increases to kOe. Then state, up remains constant to 10 kOe. The total roughly up KMHz 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 <ul style="display: flex;"><li style="flex:1">of </li><li style="flex:1">pulsed </li></ul>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, pdensity VR Rayleigh He3 and ÅR liquefying gaz slowly and the of the avelocity 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 <ul style="display: flex;"><li style="flex:1">the </li><li style="flex:1">adjust </li></ul>adecrease 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. 2shows such aAs 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 ITable 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 Kroughly 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 Kof 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 aand 2aminimum before its calculated value 1. At 0.4 KGallium vely reaching obtained from eq. final value the minimum corres- is Tis the wave. Fand 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 athere is If, sample. sample, to it is then instead ofa semi-infinite media, reflections. necessary the consider such wave radiates Schematically Rayleigh awave 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 avalue. 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 ddestructive 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 xindeed aattenuation gives negligible minimum if attenuation 2 d ^~ Thus the maxi- ~p. MHz. At 0.4 at 80 Kto 510-3 equal (Ga dB/cm mumand the minimum of the attenuation in 2figure is then the attenuation superconducting), by would and to athickness of film correspond 0.5 ~ ~,F/4 He3 versus does not deviate liquid frequency appre- if the /!.F/2 1 ~ respectively. Experimentally, from alinear law in with ciably agreement longer proportional what weare (1). to eq. film thickness was well defined there would be absorp- At 1.2 Kthe 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 aonly 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 ainteresting 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, NewYork) 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., <ul style="display: flex;"><li style="flex:1">[8] </li><li style="flex:1">[3] </li></ul>[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

Rayleigh Sound Wave Propagation on a Gallium Single Crystal in a Liquid He3 Bath G

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