Magnetic Prehistory in the Heat Capacity of the Low-Temperature Superconductors

2015 ◽  
Vol 233-234 ◽  
pp. 741-744
Author(s):  
Sergey Mikhailovich Podgornykh
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Ring Specimen ◽  
Trapped Flux ◽  
The Magnetic Field

Effect of the magnetic prehistory on the temperature dependence of the heat capacity of the superconducting Pb, La, Sn. has been studied. As soon as the external magnetic field riches the valueHext=HCthe superconductivity is completely destroyed. The trapped flux was produced in the ring specimen after the magnetic field was turned off atT<TC. We observed a difference of the value of the heat capacity between zero field cooled (ZFC) and field cooled (FC) states in zero magnetic field for the ring specimen. It is found that the FC heat capacity is smaller than the heat capacity both in the normal and in superconducting states.

scholarly journals Non-local terahertz photoconductivity in the topological phase of Hg1−xCdxTe

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. S. Kazakov ◽  
A. V. Galeeva ◽  
A. I. Artamkin ◽  
A. V. Ikonnikov ◽  
L. I. Ryabova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Laser Pulses ◽  
Zero Magnetic Field ◽  
Zero Field ◽  
Topological Phase ◽  
Non Local ◽  
Dark Signal ◽  
The Magnetic Field

AbstractWe report on observation of strong non-local photoconducitivity induced by terahertz laser pulses in non-zero magnetic field in heterostructures based on Hg1−xCdxTe films being in the topological phase. While the zero-field non-local photoconductivity is negligible, it is strongly enhanced in magnetic fields ~ 0.05 T resulting in appearance of an edge photocurrent that exceeds the respective dark signal by orders of magnitude. This photocurrent is chiral, and the chirality changes every time the magnetic field or the electric bias is reversed. Appearance of the non-local terahertz photoconductivity is attributed to features of the interface between the topological film and the trivial buffer.

Nanocomposites For magnetic Refrigeration

1992 ◽  
Vol 286 ◽  
Author(s):  
R.D. Shull ◽  
R.D. Mcmichael ◽  
J.J. Ritter ◽  
L.H. Bennett
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
External Magnetic Field ◽  
Magnetocaloric Effect ◽  
Spin System ◽  
Entropy Change ◽  
Magnetic Nanocomposites ◽  
Magnetic Entropy ◽  
Effect Data ◽  
The Magnetic Field

ABSTRACTUpon the application of an external magnetic field, the magnetic spins in a material partially align with the field, thereby reducing the magnetic entropy of the spin system. When performed adiabatically, the specimen's temperature will rise. This temperature rise, δT, related to the entropy change by the heat capacity, is known as the magnetocaloric effect. Upon cycling the magnetic field, this effect can be used for transferring heat from one thermal reservoir to another, forming the basis for a magnetic refrigerator. Recently, NIST scientists predicted composite magnetic materials containing nanometer-size magnetic species could possess enhanced magnetocaloric effects [1-2], especially at high temperatures or low magnetic fields. Magnetic nanocomposites may be prepared in many different ways, and recent magnetocaloric effect data measured on Fe-doped gadolinium gallium garnets are presented to show both the effect of processing and a methodology for optimizing δT.

ZERO FIELD ENTANGLEMENT IN DIPOLAR COUPLING SPIN SYSTEM AT NEGATIVE TEMPERATURE

2013 ◽  
Vol 11 (05) ◽  
pp. 1350050 ◽  
Author(s):  
GREGORY B. FURMAN ◽  
VICTOR M. MEEROVICH ◽  
VLADIMIR L. SOKOLOVSKY
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Spin System ◽  
Dipolar Coupling ◽  
Negative Temperature ◽  
Absolute Temperature ◽  
Zero Magnetic Field ◽  
Entangled States ◽  
Zero Field ◽  
Negative Temperatures

A dipolar coupled spin system can achieve internal thermodynamic equilibrium states at negative absolute temperature. We study analytically and numerically the temperature dependence of the concurrence in a dipolar coupled spin-1/2 system in both nonzero and zero fields and show that, at negative temperatures, entangled states can exist even in zero magnetic field.

Optische Kernspin Polarisation (ONP) in Anthracen dotiert mit Phenazin im Temperaturbereich 1,4…300 K / Optical Nuclear Polarisation (ONP) in Anthracene doped with Phenazine in the Temperature Range 1.4…300 K

1977 ◽  
Vol 32 (6) ◽  
pp. 652-658 ◽  
Author(s):  
G. Dittrich ◽  
D. Stehlik ◽  
H. Hausser
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Zero Field ◽  
Triplet States ◽  
Prominent Feature ◽  
Zero Field Splitting ◽  
Principal Axes ◽  
Characteristic Features ◽  
Anthracene Crystal ◽  
The Magnetic Field

Abstract ONP of proton spins in anthracene doped with 1000 ppm phenazine has been measured as a function of the external magnetic field Hp and its orientation with respect to the crystalline axes for the temperatures: 300, 78, 4.2 and 1.4 K. At 300 K characteristic features in magnetic fields up to 150 G are similar to results observed in doped fluorene crystals. They are interpreted as due to ONP as a consequence of level anti-crossing (LAC) in the triplet state of guest-host complexes. The zero-field splitting tensor is: D*= ±0.0101 (2) cm-1, ∣E*∣≲∣ ± 0.000811 cm-1 with the principal axes z* ∥ b, y* and x* in the ac-plane with ∢ (y*, a) =30 + 1°. No complex formation is observed at or below 78 K.The most prominent feature at all temperatures is the field dependence of ONP when the magnetic field is oriented along the projection of the long molecular in-plane axes of the anthracene molecules. The excitable triplet states in the doped anthracene crystal are discussed in terms of their qualification as ONP-active states.

Carbon and Oxygen Atoms Distribution along Low-Temperature Plasma Torch in the Magnetic Field

2015 ◽  
Vol 1084 ◽  
pp. 93-96
Author(s):  
Vyacheslav F. Myshkin ◽  
Dmitry A. Izhoykin ◽  
Eugeny V. Bespala ◽  
Ivan A. Ushakov
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Plasma Torch ◽  
Gas Mixture ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Atomic Lines ◽  
The Magnetic Field ◽  
Oxygen Atoms

The atomic lines intensity of carbon and oxygen in low-temperature plasma are shown. Measurements are made at different distances from the electrode depending on the composition of the plasma forming gas mixture and external magnetic field presence.

MATHEMATICAL MODELING OF TEMPERATURE EFFECT ON THE FAN CHART OF MAGNETOABSORPTION SPECTRUM IN SEMICONDUCTORS

2019 ◽  
pp. 104-115
Author(s):  
G. Gulyamov ◽  
U. I. Erkaboev ◽  
A. G. Gulyamov
Keyword(s):  
Mathematical Modeling ◽  
Magnetic Field ◽  
Temperature Dependence ◽  
Density Of States ◽  
Landau Levels ◽  
Joint Density ◽  
Narrow Gap ◽  
Narrow Gap Semiconductors ◽  
Dispersion Law ◽  
The Magnetic Field

The article considers the oscillations of interband magneto-optical absorption in semiconductors with the Kane dispersion law. We have compared the changes in oscillations of the joint density of states with respect to the photon energy for different Landau levels in parabolic and non-parabolic zones. An analytical expression is obtained for the oscillation of the combined density of states in narrow-gap semiconductors. We have calculated the dependence of the maximum photon energy on the magnetic field at different temperatures. A theoretical study of the band structure showed that the magnetoabsorption oscillations decrease with an increase in temperature, and the photon energies nonlinearly depend on a strong magnetic field. The article proposes a simple method for calculating the oscillation of joint density of states in a quantizing magnetic field with the non-quadratic dispersion law. The temperature dependence of the oscillations joint density of states in semiconductors with non-parabolic dispersion law is obtained. Moreover, the article studies the temperature dependence of the band gap in a strong magnetic field with the non-quadratic dispersion law. The method is applied to the research of the magnetic absorption in narrow-gap semiconductors with nonparabolic dispersion law. It is shown that as the temperature increases, Landau levels are washed away due to thermal broadening and density of states turns into a density of states without a magnetic field. Using the mathematical model, the temperature dependence of the density distribution of energy states in strong magnetic fields is considered. It is shown that the continuous spectrum of the density of states, measured at the temperature of liquid nitrogen, at low temperatures turns into discrete Landau levels. Mathematical modeling of processes using experimental values of the continuous spectrum of the density of states makes it possible to calculate discrete Landau levels. We have created the three-dimensional fan chart of magneto optical oscillations of semiconductors with considering for the joint density of energy states. For a nonquadratic dispersion law, the maximum frequency of the absorbed light and the width of the forbidden band are shown to depend nonlinearly on the magnetic field. Modeling the temperature  dependence allowed us to determine the Landau levels in semiconductors in a wide temperature spectrum. Using the proposed model, the experimental results obtained for narrow-gap semiconductors are analyzed. The theoretical results are compared with experimental results.

A 3 T superconducting magnet for long-run magnetic Compton-scattering experiments

1998 ◽  
Vol 5 (3) ◽  
pp. 937-939 ◽  
Author(s):  
Nobuhiko Sakai ◽  
Hiroshi Ohkubo ◽  
Yasushi Nakamura
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Compton Scattering ◽  
Superconducting Magnet ◽  
Field Direction ◽  
Compton Profile ◽  
Magnetic Field Direction ◽  
Long Run ◽  
Radiation Shields ◽  
The Magnetic Field

A 3 T superconducting magnet has been designed and constructed for magnetic Compton-profile (MCP) measurements with the new capabilities that the magnetic field direction can be altered quickly (within 5 s) and liquid-He refill is not required for more than one week. For the latter capability, two refrigerators have been directly attached to the cryostat to maintain the low temperature of the radiation shields and for the recondensation of liquid He. The system has been satisfactorily operated for over one week.

The Effect of Magnetic Field on the Hydration of Nanoscopic Hydrophobic N-Alkane Plates

2011 ◽  
Vol 228-229 ◽  
pp. 1007-1011
Author(s):  
Wei Wei Zhang ◽  
Long Qiu Li ◽  
Guang Yu Zhang ◽  
Hui Juan Dong
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Dynamics Simulation ◽  
Free Energy Barrier ◽  
Confined Water ◽  
Magnetic Exposure ◽  
Hydrophobic Solutes ◽  
The Magnetic Field ◽  
Density Of Water ◽  
Induced Adsorption

The effect of an external magnetic field on the hydration behavior of nanoscopic n-octane plates has been extensively investigated using molecular dynamics simulation in an isothermal-isobaric ensemble. The solute plates with different intermolecular spacing have also been considered to examine the effect of the topology of hydrophobic plates on the adsorption behavior of confined water in the presence of an external magnetic field with an intensity ranging from 0.1T to 1 T. The results demonstrate that magnetic exposure decreases the density of water for the plates with intermolecular spacing of a0 = 4 and 5 Å. This suggests that the free energy barrier for evaporation can be lowered by the applied field, and the hydrophobic solutes consisting of condensed n-octane molecules are apt to aggregate in the aqueous solution. In contrast, the magnetic field improves the dissolution or wetting of solutes comprised of loosely packed n-octane plates of a0=7Å. A magnetic-field-induced adsorption-to-desorption translation, which is in agreement with the experimental results provided by Ozeki, has also been observed for the plates with intermolecular spacing of a0 = 6 Å.

EFFECT OF DISORDER ON THE ELECTRICAL PROPERTIES OF AMORPHOUS CONDUCTING CARBON FILMS: OBSERVANCE OF FIELD INDUCED METAL-INSULATOR TRANSITION?

2000 ◽  
Vol 14 (02n03) ◽  
pp. 224-229 ◽  
Author(s):  
V. MEENAKSHI ◽  
S. V. SUBRAMANYAM
Keyword(s):  
Magnetic Field ◽  
Electrical Properties ◽  
External Magnetic Field ◽  
Low Temperature ◽  
Carbon Films ◽  
Electronic Systems ◽  
Metal Insulator Transition ◽  
Preparation Temperature ◽  
Metal Insulator ◽  
Effect Of Disorder

In this work, the influence of disorder on the electrical properties (DC conductivity and Magnetoresistance) of amorphous conducting carbon films, prepared by the pyrolysis of Tetra chloro phthalic anhydride, is reported and discussed. The low temperature electrical properties are analyzed in terms of the various models developed for disordered electronic systems. The results indicate the possibility of a metal - insulator (M-I) transition, both as a function of preparation temperature and an external magnetic field.

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