Low temperature specific heat of quench-condensed amorphous Sn1-x Cu x -films

Dutzi, Julian; Buckel, W.

doi:10.1007/bf01420560

Cited by 21 publications

(12 citation statements)

References 15 publications

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“…A close agreement of the measured electronic specific heat coefficient of the (Ago.sCuo.5)loo-xGex metallic glasses (20 S x S 25) with the free electron value has already been taken as an indication that the DOS at EF is at least 20-30% lower than the free electron value [12]. It has been stated that amorphous Culoo-xSnx also shows a depressed electronic density of states at EF [28]. However, recent specific heat measurements on Aulm-xSnx, with and without magnetic field, and a careful correction for non-electronic contributions due to low-lying excitations and for electron-phonon enhancement effects show excellent agreement with the free electron value [29].…”

Section: Resultssupporting

confidence: 53%

Photoemission valence-band structure of Hume-Rothery-type metallic glasses

Boyen¹,

Häußler²,

Baummann³

et al. 1990

J. Phys.: Condens. Matter

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Photoemission spectra of the valence-band of Hume-Rothery-type Ag45Cu35Ge20 and Ag37.5Cu37.5Ge25 metallic glasses are reported. In the present measurements and in contrast to previous measurements on liquid-quenched samples of these alloys the authors avoid any sputter-cleaning procedure prior to the spectroscopy by vapour quenching the samples in the preparation chamber of the spectrometer. Whereas in the liquid-quenched samples no indications of distinct structure-induced effects in the electronic density of states near EF have been observed, in the new samples the existence of a minimum can clearly be seen and so the earlier conclusion is partly corrected by this paper. Structural influences on the density of states exist and can be detected by photoelectron spectroscopy in electronic states with large dispersion such as s and p states. In addition they show that the decrease of the density of states towards EF cannot be discussed in terms of sp-d hybridization effects as stated previously.

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Section: Resultssupporting

confidence: 53%

Photoemission valence-band structure of Hume-Rothery-type metallic glasses

Boyen¹,

Häußler²,

Baummann³

et al. 1990

J. Phys.: Condens. Matter

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“…The influence of the copper concentration on the values of the critical temperature. The grey points represent the experimental results obtained in the papers: [4], [17], [18], [19], and [20]. The black lines have been obtained with the use of the McMillan and Allen-Dynes formulas [21], [22].…”

Section: Figmentioning

confidence: 99%

“…3. The critical temperature changes over the fairly wide range from 3.9 K to 7 K. Nevertheless, the full Eliashberg formalism allows us to reproduce the experimental results with a very good approximation [4], [17], [18], [19], [20]. Additionally, let us point out that the values of T C determined with the use of the approximated McMillan or Allen-Dynes formulas are significantly understated [21], [22].…”

mentioning

confidence: 99%

Superconducting properties of tin-copper amorphous thin films

Drzazga¹,

Szczȩśniak²,

Domagalska³

2016

Preprint

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The thermodynamic properties of the superconducting state in the amorphous Sn1−xCux thin films have been characterized. The concentration of copper changes in the range from 0.08 to 0.41. The calculations have been conducted in the framework of the strong-coupling formalism, wherein the Eliashberg functions determined in the tunnel experiment (Phys. Rev. B 51, 685 (1995)) have been used. The value of the Coulomb pseudopotential equal to 0.1 has been adopted. It has been found that the critical temperature (TC ) decreases from 7 K to 3.9 K. The ratio of the energy gap to the critical temperature: R∆ = 2∆ (0) /kBTC, differs significantly from the BCS value: R∆ ∈ 4.4, 3.95 . Similarly behaves the ratio of the specific heat jump to the specific heat of the normal state: RC = ∆C (TC ) /C N (TC ), and the parameter: RH = TC C N (TC ) /H 2 C (0), where HC (0) is the thermodynamic critical field. In particular, RC ∈ 2.2, 1.75 and RH ∈ 0.141, 0.154 .

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“…Deviations from the FEM for these alloys can be attributed to a structural influence. Besides, photoelectron spectroscopy deviations were found in the Hall effect of AHR alloys [4] and in the electronic specific heat of a-Cu x Sn 100−x [6]. They are most pronounced for high noble-metal content.…”

Section: Introductionmentioning

confidence: 98%

“…The purpose of this investigation is twofold. Firstly, we extend measurements of the specific heat C of a-Cu x Sn 100−x in zero field [6] to magnetic fields higher than the critical field B c2 (T ). This allows us to measure the electronic contribution to C in the normal state at temperatures below the superconducting transition temperature T c and to achieve therefore a higher accuracy.…”

Section: Introductionmentioning

confidence: 99%

The specific heat and upper critical field of amorphous - electronic and vibrational excitations

Sohn¹,

Baumann²

1996

J. Phys.: Condens. Matter

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The specific heat C of amorphous films was investigated between 0.3 K and 7 K in the superconducting state as well as in the normal state using a modified AC method. The analysis of the data allows one to determine the electronic density of states at the Fermi energy , the density of states of low-energy excitations and the Debye temperature . The concentration dependence of shows a pronounced minimum at x = 60 at.% in comparison to the free-electron model, in agreement with specific heat and UPS measurements and theoretical calculations published recently. The specific heat of the low-energy excitations is of the same order of magnitude as data available from the literature, and shows a linear temperature dependence. increases with copper concentration and the values agree with those published recently. In addition, the critical magnetic field of the same films was measured. The analysis of these data which should be valid for strongly disordered superconductors yields values of which are about 20% higher than those determined by specific heat measurements. Arguments are given as to why values taken from critical field measurements might be too high. Finally, the specific heat of an amorphous film was measured. was found to be 30% below the free-electron model value, in contrast to results published previously by Rieger and Baumann who found to be in accordance with the free-electron model.

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Low temperature specific heat of quench-condensed amorphous Sn1-x Cu x -films

Cited by 21 publications

References 15 publications

Photoemission valence-band structure of Hume-Rothery-type metallic glasses

Photoemission valence-band structure of Hume-Rothery-type metallic glasses

Superconducting properties of tin-copper amorphous thin films

The specific heat and upper critical field of amorphous - electronic and vibrational excitations

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