scholarly journals Sensitivity of the superconducting state in thin films

2019 ◽  
Vol 5 (3) ◽  
pp. eaau3826 ◽  
Author(s):  
I. Tamir ◽  
A. Benyamini ◽  
E. J. Telford ◽  
F. Gorniaczyk ◽  
A. Doron ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Low Temperatures ◽  
Superconducting Films ◽  
Theoretical Explanation ◽  
Two Dimensions ◽  
Metallic State ◽  
External Radiation ◽  
External Perturbations ◽  
Extreme Sensitivity

For more than two decades, there have been reports on an unexpected metallic state separating the established superconducting and insulating phases of thin-film superconductors. To date, no theoretical explanation has been able to fully capture the existence of such a state for the large variety of superconductors exhibiting it. Here, we show that for two very different thin-film superconductors, amorphous indium oxide and a single crystal of 2H-NbSe2, this metallic state can be eliminated by adequately filtering external radiation. Our results show that the appearance of temperature-independent, metallic-like transport at low temperatures is sufficiently described by the extreme sensitivity of these superconducting films to external perturbations. We relate this sensitivity to the theoretical observation that, in two dimensions, superconductivity is only marginally stable.

Transformations in Thin Solid Layers: The Reversible Polymerization-Depolymerization of 2,6-Di-n-propyl- 1,3,5,7-tetraoxa-2,6-dibora-4,8-octalindiones at Low Temperatures

1985 ◽  
Vol 40 (2) ◽  
pp. 222-228 ◽  
Author(s):  
Mohamed Yalpani ◽  
E. Klotzbücher
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Title Compound ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Visible Spectroscopy ◽  
Varying Thickness ◽  
Spontaneous Formation ◽  
Uv Visible ◽  
Lattice Energies

The course of Aggregation of molecules of the title compound (1b) through different, spectroscopically discernible and chemically identifiable forms of associations could be followed by matrix isolation and thin film infrared and UV-visible spectroscopy. It was found that molecules of 1b in thin films form clusters which at low temperatures interact weakly, probably through the carbonyl oxygens of one and the boron atoms of the neighbouring molecules. On warming to 260 K this association gradually takes the form of more defined chelate bonds, probably with ordered three-dimensional intermolecular structures. Above this temperature spontaneous formation of crystallites of the previously reported ʻhotʼ and ʻcoldʼ modifications was observed. Studies with films of varying thickness indicate an interdependence of crystallite size and lattice energies.

Substantiation of a Technique of Determining Stress in Thin Films at Very Low Temperatures

2015 ◽  
Vol 14 ◽  
pp. 28-36
Author(s):  
C.C. Chama
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Low Temperatures ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Temperature Stress ◽  
Hysteresis Curves ◽  
Stress Hysteresis

Substantiation of a technique earlier employed in determining stress in Copper-Silver thin films at very low temperatures is presented. It is shown that the stress measured at elevated temperatures using Stoney’s equation can be utilized in the determination of stress at very low temperatures. To demonstrate the application of this technique, a case study has been conducted by utilizing stress hysteresis curves obtained from the Cu-6at%Ag thin film heated from room temperature to 400°C and cooled back to room temperature in two cycles. The stresses in the Cu-6at%Ag thin film at various low temperatures up to-197°C have been determined by utilizing data from high temperature stress hysteresis curves.

In Situ FT-IR Studies of Oxide and Oxynitride Sol-Gel-Derived Thin Films

1984 ◽  
Vol 32 ◽  
Author(s):  
David M. Haaland ◽  
C. Jeffrey Brinker
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Temperature ◽  
Low Temperatures ◽  
Sol Gel ◽  
Ir Studies ◽  
Oxynitride Glass ◽  
Vibrational Bands ◽  
Ft Ir

ABSTRACTA high-temperature infrared cell was developed to study the gel-to-glass conversion of sol-gel-derived thin films. FT-IR spectra of matched thin-film borosilicate sol-gel samples were taken as the samples were heated at 100°C intervals to 700°C in either air or ammonia. The gels were converted to oxide and oxynitride glasses, respectively, by these heat treatments. The gel-to-glass conversion could be followed and compared for these two treatments by monitoring changes in the vibrational bands present in the spectra. Comparisons between the infrared spectra of NH3-treated and air-treated films heated above 500°C reveal the appearance of new B-N bonds at the expense of B-O-Si bonds for the NH3-fired films. These spectra also exhibit changes which may indicate the formation of Si-N bonds. Thus, ammonolysis reactions can result in thin-film oxynitride glass formation at relatively low temperatures.

Formation of nanoclusters on polymer thin films

1991 ◽  
Vol 49 ◽  
pp. 1122-1123
Author(s):  
Janet L. Burns ◽  
Charles J. Echert ◽  
Richard J. Spontak
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Low Temperatures ◽  
Polymeric Materials ◽  
Polymeric Films ◽  
Film Casting ◽  
Adhesive Properties ◽  
Transmission Electron ◽  
Structure Morphology

Several different techniques are currently employed for producing thin polymeric films for study in transmission electron microscopy (TEM), but the two most common routes are (cryo) ultramicrotomy and thin-film casting. Sections obtained from embedded samples or at low temperatures are valuable in correlating observed microstructure with bulk physical properties, without concern over non-equilibrium issues. However, thin-film casting is often equally useful, especially if there exists an interest in structure morphology at surfaces, which may help to elucidate surface (e.g., adhesive) properties of the material. In either case, resulting thin films can be further processed on TEM grids prior to imaging. Normally this additional step requires subjecting a film to an elevated temperature (T) for a predetermined period of time (t). Unlike most metals which are annealed at relatively high temperatures (>500° C) and most biological systems which are heated to temperatures typically less than 100° C, many polymeric materials are often subjected to temperatures between 100° and 400° C.

scholarly journals Моделирование процесса теплоотдачи сверхпроводящих пленок в резистивном состоянии

2021 ◽  
Vol 91 (3) ◽  
pp. 538
Author(s):  
М.А. Васютин ◽  
Н.Д. Кузьмичев ◽  
Д.А. Шилкин
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Low Temperatures ◽  
Heat Removal ◽  
Superconducting Films ◽  
Resistive State ◽  
Additional Heat ◽  
Film Substrate ◽  
Main Factor

The analysis of heat transfer in the contact-film-substrate system under conditions when the heat removal from the sample to the substrate is insufficient to ensure that the sample is not overheated. For low temperatures, a method is proposed for increasing the heat removal from thin-film samples by passing a high-density electric current through them. The property of an anomalously high thermal conductivity of copper at temperatures from 5 to 50 K was used as the main factor in enhancing heat removal. The heat equation for the film-substrate system was numerically solved under the condition of additional heat transfer to potential contacts. It has been shown that beryllium bronze contacts can provide efficient heat removal from samples of superconducting films in a resistive state under conditions of strong Joule heat release.

scholarly journals Low Temperature Deposition of Metal Oxide Thin Films in Supercritical Carbon Dioxide Using Metal-organic Precursors

2007 ◽  
Vol 1007 ◽  
Author(s):  
Theodosia Gougousi ◽  
Zhiying Chen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Low Temperatures ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Metal Organic ◽  
Organic Precursors ◽  
Supercritical Carbon

ABSTRACTA novel chemical route in thin film formation that includes the use of inorganic and organic peroxides and metal organic complexes soluble in supercritical carbon dioxide has been investigated for the deposition of alumina, titania and zirconia thin films at low temperatures (<150°C). The metal organic precursors used include: Al(acac)3, OTi(tmhd)2, and Zr(acac)4. Tert-butyl peroxide, and a 30% aqueous solution of hydrogen peroxide were used as oxidants. Depositions were carried out in a 25 ml hot wall reactor at pressures ranging from 2100 to 3900 psi at 80-140°C. The deposited thin films were investigated by using X-ray photoelectron spectroscopy (XPS) and transmission Fourier transform infrared spectroscopy (FTIR). XPS and FTIR results indicate the formation of metal oxides thin films with some bonded carbon. The deposition temperatures achieved in this process are substantially lower than those used in conventional vacuum deposition techniques making feasible the deposition on temperature sensitive substrates and organic materials required for the development of hybrid organic/inorganic devices. Processing at low temperatures in supercritical carbon dioxide may provide the basis for the development of an alternative, environmentally friendly, thin film deposition technique for the processing of nanostructures.

Phonon Thermodynamics in Crystalline Nanofilms

2007 ◽  
Vol 555 ◽  
pp. 291-296 ◽  
Author(s):  
J.P. Šetrajčić ◽  
V.M. Zorić ◽  
S.M. Vučenović ◽  
D.Lj. Mirjanić ◽  
V.D. Sajfert ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Activation Energy ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Density Of States ◽  
Ultrathin Films ◽  
Low Temperatures ◽  
Specific Conductivity ◽  
Dispersion Law

The dispersion law and density of states of phonons in ultrathin films was analyzed in this paper. It turned out that phonons in a thin film require activation energy for exciting. This leads to extremely low specific heat and specific conductivity at low temperatures. Consequences of quoted facts were discussed in detail and their influence on kinetic and thermodynamic properties of thin films is estimated.

Thermoelectric power of oriented thin-film organic conductors

RSC Advances ◽  
2016 ◽  
Vol 6 (47) ◽  
pp. 41040-41044 ◽  
Author(s):  
Ryonosuke Sato ◽  
Yasuhiro Kiyota ◽  
Tomofumi Kadoya ◽  
Tadashi Kawamoto ◽  
Takehiko Mori
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Temperature Dependence ◽  
Thermoelectric Power ◽  
Low Temperatures ◽  
Organic Conductors

The temperature dependence of thermoelectric power is investigated down to low temperatures for oriented thin films of organic conductors.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Observations on the growth of YBa2Cu3O7-δ thin films on MgO by pulsed-laser ablation

1991 ◽  
Vol 49 ◽  
pp. 1068-1069
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Laser Ablation ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Laser Ablation Process ◽  
Deposition Parameters

Pulsed-laser ablation has been widely used to produce high-quality thin films of YBa2Cu3O7-δ on a range of substrate materials. The nonequilibrium nature of the process allows congruent deposition of oxides with complex stoichiometrics. In the high power density regime produced by the UV excimer lasers the ablated species includes a mixture of neutral atoms, molecules and ions. All these species play an important role in thin-film deposition. However, changes in the deposition parameters have been shown to affect the microstructure of thin YBa2Cu3O7-δ films. The formation of metastable configurations is possible because at the low substrate temperatures used, only shortrange rearrangement on the substrate surface can occur. The parameters associated directly with the laser ablation process, those determining the nature of the process, e g. thermal or nonthermal volatilization, have been classified as ‘primary parameters'. Other parameters may also affect the microstructure of the thin film. In this paper, the effects of these ‘secondary parameters' on the microstructure of YBa2Cu3O7-δ films will be discussed. Examples of 'secondary parameters' include the substrate temperature and the oxygen partial pressure during deposition.

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