scholarly journals Vortex Dynamics and Superconducting Phase Diagrams in Ta x Ge 1-x / Ge Multilayers with Coplanar Defects

2021 ◽  
Author(s):  
◽  
Andreas Engel
Keyword(s):  
Low Temperature ◽  
Magnetic Fields ◽  
Phase Diagrams ◽  
Glass Phase ◽  
High Vacuum ◽  
Strong Support ◽  
Superconducting Phase ◽  
Field Orientation ◽  
Current Voltage ◽  
Zero Resistance

<p>The superconducting phase diagrams of amorphous multilayered Ta x Ge 1-x / Ge thin films have been studied over a large range of temperatures and magnetic fields by means of dc electrical transport measurements. These superconducting films belong to the class of extremely type-II superconductors, for which a multitude of superconducting phases has been predicted and experimentally verified. A thorough understanding of these phase diagrams is indispensable for future successful applications of high-temperature superconductors since some of the observed phases severely limit the zero-resistance current-carrying capacity of these materials. The Ta x Ge 1-x / Ge films in this study were prepared by vapour deposition under high vacuum conditions. The Ta-content varied between x = 0.31 and 0.37 and individual layer thicknesses ranged from about 3 to 15 nm. Tilting the sample substrates during the deposition resulted in coplanar defects with variable orientation and structure depending on the tilting angle. This way it was possible to study the interplay between magnetic flux lines and the material structure and defect morphology, respectively. Films with thin insulating Ge layers and thus strong interlayer coupling showed three dimensional behaviour over the complete range of fields and temperatures. The coplanar defect structure was able to extend the zero-resistance phase to significantly higher fields and temperatures for magnetic fields co-aligned with the defects. Strong support for the existence of a low-temperature glass phase was found in the case of aligned and misaligned magnetic fields. Increasing the insulating layer thickness lead to a cross-over to 2D behaviour depending on temperature and field as well as field orientation with respect to the defects. In the 2D phase regions the low-temperature zero-resistance glass phase may have disappeared entirely. Current-voltage characteristics measured in the low-temperature glass phases showed significant differences between the strongly and weakly coupled films. However the detailed temperature and field dependence of these current-voltage curves at low temperatures cannot be explained satisfactorily with existing theoretical models.</p>

scholarly journals Vortex Dynamics and Superconducting Phase Diagrams in Ta x Ge 1-x / Ge Multilayers with Coplanar Defects

2021 ◽  
Author(s):  
◽  
Andreas Engel
Keyword(s):  
Low Temperature ◽  
Magnetic Fields ◽  
Phase Diagrams ◽  
Glass Phase ◽  
High Vacuum ◽  
Strong Support ◽  
Superconducting Phase ◽  
Field Orientation ◽  
Current Voltage ◽  
Zero Resistance

<p>The superconducting phase diagrams of amorphous multilayered Ta x Ge 1-x / Ge thin films have been studied over a large range of temperatures and magnetic fields by means of dc electrical transport measurements. These superconducting films belong to the class of extremely type-II superconductors, for which a multitude of superconducting phases has been predicted and experimentally verified. A thorough understanding of these phase diagrams is indispensable for future successful applications of high-temperature superconductors since some of the observed phases severely limit the zero-resistance current-carrying capacity of these materials. The Ta x Ge 1-x / Ge films in this study were prepared by vapour deposition under high vacuum conditions. The Ta-content varied between x = 0.31 and 0.37 and individual layer thicknesses ranged from about 3 to 15 nm. Tilting the sample substrates during the deposition resulted in coplanar defects with variable orientation and structure depending on the tilting angle. This way it was possible to study the interplay between magnetic flux lines and the material structure and defect morphology, respectively. Films with thin insulating Ge layers and thus strong interlayer coupling showed three dimensional behaviour over the complete range of fields and temperatures. The coplanar defect structure was able to extend the zero-resistance phase to significantly higher fields and temperatures for magnetic fields co-aligned with the defects. Strong support for the existence of a low-temperature glass phase was found in the case of aligned and misaligned magnetic fields. Increasing the insulating layer thickness lead to a cross-over to 2D behaviour depending on temperature and field as well as field orientation with respect to the defects. In the 2D phase regions the low-temperature zero-resistance glass phase may have disappeared entirely. Current-voltage characteristics measured in the low-temperature glass phases showed significant differences between the strongly and weakly coupled films. However the detailed temperature and field dependence of these current-voltage curves at low temperatures cannot be explained satisfactorily with existing theoretical models.</p>

The Low Temperature Phases of 3He

1982 ◽  
Vol 19 ◽  
Author(s):  
Robert C. Richardson
Keyword(s):  
Low Temperature ◽  
Magnetic Fields ◽  
Phase Diagrams ◽  
Temperature Range ◽  
Two Systems

ABSTRACTIn the temperature range between 1 mK and 3 mK and in magnetic fields between 0 T and 1 T, there are four distinct phases of liquid 3He and three distinct phases of solid 3He. The liquid becomes a triplet superfluid and the solid becomes a nuclear antiferromagnet. Despite the great differences which exist between a superfluid and an antiferromagnet, there are remarkable similarities between phase diagrams of the two systems.

OBSERVATION OF THERMALLY RECYCLEABLE ZERO-RESISTANCE STATES IN YBaCuO ABOVE DRY ICE TEMPERATURES

1989 ◽  
Vol 03 (16) ◽  
pp. 1197-1206 ◽  
Author(s):  
J. T. CHEN ◽  
L.-X. QIAN ◽  
L.-Q. WANG ◽  
L. E. WENGER ◽  
E. M. LOGOTHETIS
Keyword(s):  
Transition Temperature ◽  
Low Temperature ◽  
Magnetic Measurements ◽  
Meissner Effect ◽  
Hysteretic Behavior ◽  
Current Voltage ◽  
Zero Resistance ◽  
Resistance State ◽  
Current Voltage Characteristics ◽  
Zero Voltage

Thermally recycleable zero-resistance states with transition temperatures above 200 K are observed in mixed-phase YBaCuO materials that are treated by a low-temperature (< 150° C ) oxygenation process and enclosed in an oxygen atmosphere during electrical and magnetic measurements. The zero-resistance state is verified through multiple lead and contact arrangements as well as by measurements of the current-voltage characteristics for several paths with the highest transition temperature (zero resistance) for any sample being 265 K and with a zero-voltage current exceeding 4.3 mA at 240 K. Although a full Meissner effect is not obtained, diamagnetic-like deviations and hysteretic behavior are observed to occur at the same temperatures as the resistive transitions. This indicates that the zero resistance, if related to superconductivity, is due to filamentary superconducting paths or materials of lower dimensionality.

High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast

1988 ◽  
Vol 46 ◽  
pp. 256-257
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Eugene L. Vigil
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Standard Specimen ◽  
High Vacuum ◽  
Specimen Holder ◽  
Sputter Coating ◽  
Fresh Frozen ◽  
Gain Access ◽  
Scanning Electron ◽  
Transfer Device

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.

scholarly journals Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Jing Wang ◽  
Zhihua Wan ◽  
Zhurong Dong ◽  
Zhengguo Li
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Performance Test ◽  
High Reliability ◽  
High Vacuum ◽  
Test System ◽  
Low Noise ◽  
Speed Ratio ◽  
Space Harmonic ◽  
Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

Magnetic Anisotropy in Single Crystals of Zn–Mn and Zn–Cr

1974 ◽  
Vol 52 (18) ◽  
pp. 1759-1764 ◽  
Author(s):  
F. T. Hedgcock ◽  
S. Lenis ◽  
P. L. Li ◽  
J. O. Ström-Olsen ◽  
E. F. Wassermann
Keyword(s):  
Low Temperature ◽  
Magnetic Fields ◽  
Magnetic Anisotropy ◽  
Single Crystals ◽  
Crystal Field ◽  
Interaction Effects ◽  
Crystal Field Splitting ◽  
High Magnetic Fields ◽  
Field Splitting ◽  
Chromium Ion

We have extended the low temperature magnetic anisotropy measurements on single crystals of zinc containing up to 600 p.p.m. manganese from magnetic fields of 9 to 56 kG. The crystal field splitting parameters determined at low magnetic fields also characterizes the magnetic anisotropy at high magnetic fields. Manganese–manganese interaction effects are observed in the magnetic anisotropy at manganese concentrations greater than 300 p.p.m. Low temperature magnetic anisotropy measurements on single crystals of zinc containing up to 164 p.p.m. chromium are reported and indicate a crystal field splitting of 0.16 K for the chromium ion.

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