scholarly journals Microwave properties of Fe(Se,Te) thin films in a magnetic field: pinning and flux flow

2020 ◽  
Vol 1559 ◽  
pp. 012055 ◽  
Author(s):  
Nicola Pompeo ◽  
Andrea Alimenti ◽  
Kostiantyn Torokhtii ◽  
Giulia Sylva ◽  
Valeria Braccini ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Microwave Properties ◽  
Flux Flow

Fabrication and characteristics of weak links between â- and ĉ-axis normal grains of Y1Ba2Cu3O7−x

1996 ◽  
Vol 11 (5) ◽  
pp. 1086-1093
Author(s):  
S. Mahajan ◽  
D. B. Buchholz ◽  
J. Lei ◽  
R. P. H. Chang ◽  
T. Hogan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Critical Current ◽  
Weak Coupling ◽  
Boundary Plane ◽  
Weak Links ◽  
Ion Milling ◽  
Flux Flow ◽  
Grain Boundary Plane ◽  
Current Voltage

We have used pulsed organometallic beam epitaxy (POMBE) to simultaneously deposit â- and ĉ-axis oriented Y1Ba2Cu3O7−x (YBCO) thin films at arbitrary locations on LaAlO3(100) substrates. Using photolithography and ion milling, several types of â-ĉ weak links have been fabricated at the boundary between the two films. The current-voltage (I-V) characteristics show a flux flow type behavior. The resistive transitions are broad and the critical current density is low, indicating weak coupling across these boundaries. With magnetic field applied parallel to the grain boundary plane, nonhysteretic I-V curves are obtained and the critical current goes to zero at an applied magnetic field of ∼7500 G.

scholarly journals New Measurements of the Transition to the Normal State Induced by High Current Densities in High-Tc Superconductor Microbridges under Thermal Smallness Conditions

2014 ◽  
Vol 95 ◽  
pp. 202-206 ◽  
Author(s):  
J.M. Doval ◽  
J. Maza ◽  
C. Torron ◽  
J.A. Veira ◽  
M. Tello ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Diffusion Length ◽  
High Current ◽  
Flux Flow ◽  
High Tc ◽  
High Tc Superconductor ◽  
Dimensional Scaling ◽  
Current Densities ◽  
Millisecond Range

We address here the superconductivity quenching under an external magnetic field of amplitudes up to 1 T and in the so-called "thermal smallness" condition, when the microbridge width becomes smaller than the thermal diffusion length of both the own superconductor and its refrigerant (the substrate, in the case of thin films), which breaks their thermal dimensional scaling. Our results further support that when the current perturbations have characteristic times in the millisecond range the quenching is due to thermal instabilities associated with regular (nonsingular) flux-flow, and they also suggest how to optimize the refrigeration of practical superconductors.

BEHAVIOUR OF ORIENTED POLYCRYSTALLINE YBaCuO SUPERCONDUCTING THIN FILMS IN A WEAK MAGNETIC FIELD

1990 ◽  
Vol 04 (15) ◽  
pp. 975-982
Author(s):  
H.H. WEN ◽  
X.W. CAO ◽  
J.Z. SHI ◽  
W.Z. SHI ◽  
W.G. YAO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Critical Field ◽  
Weak Magnetic Field ◽  
Flow Resistance ◽  
Weak Links ◽  
Superconducting Thin Films ◽  
Flux Flow ◽  
Granular Superconductivity ◽  
Oriented Polycrystalline

We determined a few characteristics of granular superconductivity through magnetoresistance measurements made on oriented polycrystalline YBaCuO superconducting thin films, and found that, at 77.3 K, the critical field for breaking a major portion of the superconducting weak links between grains was about 80 G, while the average lower critical field of the grains was about 175 G. Detail analyses on flux flow resistance show that a maximum of the increasing of flux flow resistance induced by a unit field will exist at a specified temperature, which we think is related to the dependence of the pinning energy on the temperature.

DC and microwave properties of YBa2Cu3Ox thin films in a weak magnetic field

1992 ◽  
Vol 202 (3-4) ◽  
pp. 243-248 ◽  
Author(s):  
M. Mahel ◽  
R. Adam ◽  
M. Darula ◽  
Š. Chromik ◽  
Š. Beňačka
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Weak Magnetic Field ◽  
Microwave Properties

Electrical Anisotropy of Thin Metal Films Growing on Dielectric Substrates

2002 ◽  
Vol 7 (2) ◽  
pp. 45-52
Author(s):  
L. Jakučionis ◽  
V. Kleiza
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Uniaxial Anisotropy ◽  
Metal Films ◽  
Thin Layers ◽  
Electrical Anisotropy ◽  
Electrical Field ◽  
Dielectric Substrates ◽  
Unequal Probability ◽  
Conductive Thin Films

Electrical properties of conductive thin films, that are produced by vacuum evaporation on the dielectric substrates, and which properties depend on their thickness, usually are anisotropic i.e. they have uniaxial anisotropy. If the condensate grow on dielectric substrates on which plane electrical field E is created the transverse voltage U⊥ appears on the boundary of the film in the direction perpendicular to E. Transverse voltage U⊥ depends on the angle γ between the applied magnetic field H and axis of light magnetisation. When electric field E is applied to continuous or grid layers, U⊥ and resistance R of layers are changed by changing γ. It means that value of U⊥ is the measure of anisotropy magnitude. Increasing voltage U0 , which is created by E, U⊥ increases to certain magnitude and later decreases. The anisotropy of continuous thin layers is excited by inequality of conductivity tensor components σ0 ≠ σ⊥. The reason of anisotropy is explained by the model which shows that properties of grain boundaries are defined by unequal probability of transient of charge carrier.

Magnetic and microwave properties of FeNi thin films of different thicknesses deposited onto cyclo olefin copolymer flexible substrates

2021 ◽  
pp. 1-1
Author(s):  
C. M. Madrid Aguilar ◽  
A. V. Svalov ◽  
A. A. Kharlamova ◽  
E. E. Shalygina ◽  
A. Larranaga ◽  
...  
Keyword(s):  
Thin Films ◽  
Microwave Properties ◽  
Flexible Substrates

The activation energy U(T,B) in high temperature superconductor

2020 ◽  
Vol 92 (2) ◽  
pp. 20601
Author(s):  
Abdelaziz Labrag ◽  
Mustapha Bghour ◽  
Ahmed Abou El Hassan ◽  
Habiba El Hamidi ◽  
Ahmed Taoufik ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Activation Energy ◽  
Phase Diagram ◽  
High Temperature ◽  
Apparent Activation Energy ◽  
High Temperature Superconductor ◽  
Flux Flow ◽  
Resistivity Measurements ◽  
Vortex Phase ◽  
The Magnetic Field

It is reported in this paper on the thermally assisted flux flow in epitaxial YBa2Cu3O7-δ deposited by Laser ablation method on the SrTiO3 substrate. The resistivity measurements ρ (T, B) of the sample under various values of the magnetic field up to 14T in directions B∥ab-plane and B∥c-axis with a dc weak transport current density were investigated in order to determine the activation energy and then understand the vortex dynamic phenomena and therefore deduce the vortex phase diagram of this material. The apparent activation energy U0 (B) calculated using an Arrhenius relation. The measured results of the resistivity were then adjusted to the modified thermally assisted flux flow model in order to account for the temperature-field dependence of the activation energy U (T, B). The obtained values from the thermally assisted activation energy, exhibit a behavior similar to the one showed with the Arrhenius model, albeit larger than the apparent activation energy with ∼1.5 order on magnitude for both cases of the magnetic field directions. The vortex glass model was also used to obtain the vortex-glass transition temperature from the linear fitting of [d ln ρ/dT ] −1 plots. In the course of this work thanks to the resistivity measurements the upper critical magnetic field Hc2 (T), the irreversibility line Hirr (T) and the crossover field HCrossOver (T) were located. These three parameters allowed us to establish a phase diagram of the studied material where limits of each vortex phase are sketched in order to optimize its applicability as a practical high temperature superconductor used for diverse purposes.

scholarly journals Effects of Perpendicular Magnetic Field Annealing on the Structural and Magnetic Properties of [Co/Ni]2/PtMn Thin Films

2021 ◽  
Vol 7 (3) ◽  
pp. 38
Author(s):  
Roshni Yadav ◽  
Chun-Hsien Wu ◽  
I-Fen Huang ◽  
Xu Li ◽  
Te-Ho Wu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Magnetic Properties ◽  
Photoelectron Spectroscopy ◽  
Perpendicular Magnetic Field ◽  
Face Centered Cubic ◽  
Lattice Image ◽  
X Ray ◽  
Field Annealing ◽  
Face Centered

In this study, [Co/Ni]2/PtMn thin films with different PtMn thicknesses (2.7 to 32.4 nm) were prepared on Si/SiO2 substrates. The post-deposition perpendicular magnetic field annealing (MFA) processes were carried out to modify the structures and magnetic properties. The MFA process also induced strong interlayer diffusion, rendering a less sharp interface between Co and Ni and PtMn layers. The transmission electron microscopy (TEM) lattice image analysis has shown that the films consisted of face-centered tetragonal (fct) PtMn (ordered by MFA), body-centered cubic (bcc) NiMn (due to intermixing), in addition to face-centered cubic (fcc) Co, Ni, and PtMn phases. The peak shift (2-theta from 39.9° to 40.3°) in X-ray diffraction spectra also confirmed the structural transition from fcc PtMn to fct PtMn after MFA, in agreement with those obtained by lattice images in TEM. The interdiffusion induced by MFA was also evidenced by the depth profile of X-ray photoelectron spectroscopy (XPS). Further, the magnetic properties measured by vibrating sample magnetometry (VSM) have shown an increased coercivity in MFA-treated samples. This is attributed to the presence of ordered fct PtMn, and NiMn phases exchange coupled to the ferromagnetic [Co/Ni]2 layers. The vertical shift (Mshift = −0.03 memu) of the hysteresis loops is ascribed to the pinned spins resulting from perpendicular MFA processes.

The influence of pressure and magnetic field on the deposition of epitaxial TiBx thin films from DC magnetron sputtering

Vacuum ◽  
2020 ◽  
Vol 177 ◽  
pp. 109355
Author(s):  
Nils Nedfors ◽  
Daniel Primetzhofer ◽  
Igor Zhirkov ◽  
Justinas Palisaitis ◽  
Per O.Å. Persson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Magnetron Sputtering ◽  
Dc Magnetron Sputtering
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