Interactions between phonon sheets in superfluid helium

Smith, D H S; Вовк, Р. В.; Williams, C. D. H.; Wyatt, A. F. G.

doi:10.1088/1367-2630/8/8/128

Cited by 46 publications

(15 citation statements)

References 30 publications

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“…The fact that the transverse coherence length turned out to be smaller (1) and (2) than the interlayer distance is consistent with published data. 3,45 We believe that this shows that at least two factors have to be taken into account: first, the spatial inhomogeneity associated with the presence of another phase, 46 which causes a nonuniform current distribution over the sample and, second, the possible influence of specific quasiparticle scattering mechanisms 8,17,[47][48][49] owing to the existence of structural and kinematic anisotropies in the system.…”

Section: Resultsmentioning

confidence: 99%

Conductivity of single-crystal Y1−yPryBa2Cu3O7−δ over a wide range of temperatures and Pr concentrations

Khadzhai

Vovk

Вовк

2014

Low Temperature Physics

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Section: Resultsmentioning

confidence: 99%

Conductivity of single-crystal Y1−yPryBa2Cu3O7−δ over a wide range of temperatures and Pr concentrations

Khadzhai

Vovk

Вовк

2014

Low Temperature Physics

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“…The bolometer was in a bridge with electronic feedback that maintained it at a constant resistance and, hence, temperature of ϳ0.35 K. [33][34][35] Recent experiments have shown that the sensitive area of the bolometer is actually only ϳ0.1 mmϫ ϳ 0.1 mm. 36 It is most likely that the sensitive region is a single superconducting-normal boundary across the track width of ϳ0.1 mm.…”

Section: Experimental Methods and Apparatusmentioning

confidence: 99%

Creation of high-energy phonons in superfluidH4eand the dependence of their angular distribution on heater size

Smith

Wyatt

2010

Phys. Rev. B

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The angular distributions of high-energy phonons, that are created by a short pulse of low-energy phonons propagating in superfluid 4 He, are measured for different heater sizes and heater powers. We find that the intrinsic full width at half height of the high-energy phonons is proportional to the reciprocal of the width of the heater that creates the low-energy phonons. This is similar to the behavior shown by the low-energy phonons where the width of the phonon sheet is inversely proportional to the heater width. We discuss the correspondence between the formation of the phonon sheet by the low-energy phonons and the creation of high-energy phonons, and conclude that the phonon sheet is caused by the creation of high-energy phonons within a few millimeters of the heater. We also show that the total energy in the high-energy phonons increases linearly with heater power, once a threshold power is reached. This indicates that the initial low-energy phonons increase in number but not energy, as the heater power is increased.

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“…Since y characterizes the total concentration of Pr which substitutes Y and Ba and causes the appearance of vacancies at the Cu positions [26], whereas d specifies the oxygen deficiency only, one can assume that the fluctuation parameters are more sensitive to the total concentration of defects than to the oxygen deficiency, that is to the defects in the CuO 2 layers. A certain role at this can be played by other specific mechanisms of quasiparticle scattering [49][50][51][52][53][54] stipulated by the presence of the structural and kinematic anisotropy in the system.…”

Section: Normal-state Resistancementioning

confidence: 99%

Effect of defects on the basal-plane resistivity of $$\hbox {YBa}_2\hbox {Cu}_3\hbox {O}_{7-\delta }$$ YBa 2 Cu 3 O 7 - δ and $$\hbox {Y}_{1-y}\hbox {Pr}_y\hbox {Ba}_2\hbox {Cu}_3\hbox {O}_{7-x}$$ Y 1 - y Pr y Ba 2 Cu 3 O 7 - x single crystals

Вовк

Khadzhai

Dobrovolskiy

et al. 2014

J Mater Sci: Mater Electron

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Temperature dependences of the basal-plane resistivity of YBa 2 Cu 3 O 7Àd single crystals with different oxygen deficiency levels d are investigated in the temperature interval T c -300 K. In this temperature range, these dependences, alike those for Y 1Ày Pr y Ba 2 Cu 3 O 7Àx with various Pr content, y, can be described with great accuracy by an expression accounting for electron scattering on phonons and defects, as well as the fluctuation conductivity within the 3D Aslamazov-Larkin model. Our analysis shows that for both compounds the scattering characteristics for the charge carriers in the layer planes are determined by defects in the CuO 2 layers, which arise owing to changes in the oxygen deficiency or in the Pr content. Our data suggest that the fluctuation parameters are affected by the total defect concentration rather than by the oxygen deficiency. The dependences T c ðdÞ for YBa 2 Cu 3 O 7Àd and T c ðyÞ for Y 1Ày Pr y Ba 2 Cu 3 O 7Àx are similar, especially for y; d\0:2, and both can be ascribed to the suppression of superconductivity by defects.

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Interactions between phonon sheets in superfluid helium

Cited by 46 publications

References 30 publications

Conductivity of single-crystal Y1−yPryBa2Cu3O7−δ over a wide range of temperatures and Pr concentrations

Conductivity of single-crystal Y1−yPryBa2Cu3O7−δ over a wide range of temperatures and Pr concentrations

Creation of high-energy phonons in superfluidH4eand the dependence of their angular distribution on heater size

Effect of defects on the basal-plane resistivity of $$\hbox {YBa}_2\hbox {Cu}_3\hbox {O}_{7-\delta }$$ YBa 2 Cu 3 O 7 - δ and $$\hbox {Y}_{1-y}\hbox {Pr}_y\hbox {Ba}_2\hbox {Cu}_3\hbox {O}_{7-x}$$ Y 1 - y Pr y Ba 2 Cu 3 O 7 - x single crystals

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