Observation of Hexagonally Ordered Flux Quanta in YBa2Cu3O7

1987 ◽  
Vol 99 ◽  
Author(s):  
P. L. Gammel ◽  
D. J. Bishop ◽  
G. J. Dolan ◽  
J. R. Kwo ◽  
C. A. Murray ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fundamental Property ◽  
Quantized Vortices ◽  
Constant Field ◽  
High Tc ◽  
Flux Lines ◽  
Show Evidence ◽  
Ordinary Type ◽  
Hexagonally Ordered ◽  
Spatially Varying

ABSTRACTThe high resolution Bitter Pattern technique has been used to reveal the structure of the array of flux lines which is present when single crystal samples of the high Tc superconductor YBa2Cu3O7 are placed in a magnetic field. At 4.2K with the magnetic field parallel to the c axis, the patterns formed are strongly reminiscent of the analogous structures in ordinary type II superconductors. The structures typically consist of flux spots with short range hexagonal correlations. We interpret the patterns to consist of singly quantized vortices. Very uniform patterns are observed in thin, flat samples cooled in a constant field. Sampling the spot density yields a vortex density consistent with a flux quantum of hc/2e.Experiments at 77K, the only other temperature studied, showed no spatially varying magnetic structure. Recent mechanical measurements which are sensitive to the bulk modulus and dissipation within the vortex lattice show evidence for a mobility transition near 75K, which would be consistent with this observation. We believe this stems from materials properties rather than some more fundamental property of the new superconductors.

scholarly journals Relativistic Landau quantization in non-uniform magnetic field and its applications to white dwarfs and quantum information

2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Srishty Aggarwal ◽  
Banibrata Mukhopadhyay ◽  
Gianluca Gregori
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Quantum Information ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Energy Levels ◽  
Landau Levels ◽  
Constant Field ◽  
Angular Momenta ◽  
Spatially Varying

We investigate the two-dimensional motion of relativistic cold electrons in the presence of `strictly’ spatially varying magnetic fields satisfying, however, no magnetic monopole condition. We find that the degeneracy of Landau levels, which arises in the case of the constant magnetic field, lifts out when the field is variable and the energy levels of spin-up and spin-down electrons align in an interesting way depending on the nature of change of field. Also, the varying magnetic field splits Landau levels of electrons with zero angular momentum from positive angular momentum, unlike the constant field which only can split the levels between positive and negative angular momenta. Exploring Landau quantization in non-uniform magnetic fields is a unique venture on its own and has interdisciplinary implications in the fields ranging from condensed matter to astrophysics to quantum information. As examples, we show magnetized white dwarfs, with varying magnetic fields, involved simultaneously with Lorentz force and Landau quantization affecting the underlying degenerate electron gas, exhibiting a significant violation of the Chandrasekhar mass-limit; and an increase in quantum speed of electrons in the presence of a spatially growing magnetic field.

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS II: Electron Spin Resonance of DPPH Coated on Y1Ba2Cu3Oy as A Probe of Magnetic Field Variations

1991 ◽  
Vol 05 (11) ◽  
pp. 779-787
Author(s):  
K. SUGAWARA ◽  
D.J. BAAR ◽  
Y. SHIOHARA ◽  
S. TANAKA
Keyword(s):  
Magnetic Field ◽  
Temporal Variations ◽  
Zero Field ◽  
High Tc ◽  
Spin Resonance ◽  
Absorption Studies ◽  
Powder Particles ◽  
Increasing Temperature ◽  
Linewidth Broadening ◽  
Magnetic Field Variations

The ESR linewidth (∆H pp ) of DPPH coated on the surface of powder specimens of Y 1 Ba 2 Cu 3 O y has been studied under various magnetic field and temperature conditions. ∆H pp increases substantially with decreasing temperature in the field cooled case, whereas almost no linewidth broadening was found in the zero field cooled case. ∆H pp was found to be sensitive to the applied magnetic field. This effect was very pronounced at temperatures lower than 40 K, but decreased strongly with increasing temperature. The broadening of the resonance lineshape has been attributed to spatial and temporal variations of the fluxon distribution in the powder particles.

Start-up of a cyclotron with a spatially varying magnetic field

Atomic Energy ◽  
1960 ◽  
Vol 6 (6) ◽  
pp. 486-487
Author(s):  
D. P. Vasilevskaya ◽  
A. A. Glazov ◽  
V. I. Danilov ◽  
Yu. N. Denisov ◽  
V. P. Zhelepov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Start Up ◽  
Spatially Varying

Direct Determination of the Velocity of Vortices in High-Tc Superconductors by a Non-Equilibrium Method

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3288-3291
Author(s):  
I. Kirschner ◽  
R. Laiho ◽  
A. C. Bódi ◽  
E. Lähderanta ◽  
I. Vajda
Keyword(s):  
Magnetic Field ◽  
Temperature Gradient ◽  
Vortex Motion ◽  
Direct Determination ◽  
Field Investigation ◽  
High Tc Superconductors ◽  
High Tc ◽  
Pinning Centers ◽  
Non Equilibrium

As is shown, thermally assisted vortex motion can come into being in high-T c superconductors due to the applied temperature gradient. Its behavior strongly depends on the local and global microstructure of the samples, moreover on the temperature and magnetic field. Investigation of the density, size and intensity of the pinning centers of specimens leads to the conclusion that the higher homogeneity immediately weakens and the lower one strenghtens the pinning, thus the former promotes and the latter impedes the vortex motion. The non-equilibrium experimental technique together with a.c. susceptibility measurements render possible the direct determination of the velocity of vortices. Depending on the actual microstructural state of samples it has the values between 6 × 10-2 mm/s and 18 × 10-2 mm/s in the case of Y-Ba-Cu-O specimens investigated.

scholarly journals K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B stars

2018 ◽  
Vol 616 ◽  
pp. A77 ◽  
Author(s):  
D. M. Bowman ◽  
B. Buysschaert ◽  
C. Neiner ◽  
P. I. Pápics ◽  
M. E. Oksala ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Intrinsic Variability ◽  
B Stars ◽  
Pulsating Stars ◽  
Chemically Peculiar ◽  
Large Scale Magnetic Field ◽  
Peculiar Stars ◽  
Show Evidence ◽  
Chemically Peculiar Stars

Context. The physics of magnetic hot stars and how a large-scale magnetic field affects their interior properties is largely unknown. Few studies have combined high-quality observations and modelling of magnetic pulsating stars, known as magneto-asteroseismology, primarily because of the dearth of detected pulsations in stars with a confirmed and well-characterised large-scale magnetic field. Aims. We aim to characterise observational signatures of rotation and pulsation in chemically peculiar candidate magnetic stars using photometry from the K2 space mission. Thus, we identify the best candidate targets for ground-based, optical spectropolarimetric follow-up observations to confirm the presence of a large-scale magnetic field. Methods. We employed customised reduction and detrending tools to process the K2 photometry into optimised light curves for a variability analysis. We searched for the periodic photometric signatures of rotational modulation caused by surface abundance inhomogeneities in 56 chemically peculiar A and B stars. Furthermore, we searched for intrinsic variability caused by pulsations (coherent or otherwise) in the amplitude spectra of these stars. Results. The rotation periods of 38 chemically peculiar stars are determined, 16 of which are the first determination of the rotation period in the literature. We confirm the discovery of high-overtone roAp pulsation modes in HD 177765 and find an additional 3 Ap and Bp stars that show evidence of high-overtone pressure modes found in roAp stars in the form of possible Nyquist alias frequencies in their amplitude spectra. Furthermore, we find 6 chemically peculiar stars that show evidence of intrinsic variability caused by gravity or pressure pulsation modes. Conclusions. The discovery of pulsations in a non-negligible fraction of chemically peculiar stars make these stars high-priority targets for spectropolarimetric campaigns to confirm the presence of their expected large-scale magnetic field. The ultimate goal is to perform magneto-asteroseismology and probe the interior physics of magnetic pulsating stars.

scholarly journals Magnetic field sensing with the kinetic inductance of a high-Tc superconductor

AIP Advances ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 045217 ◽  
Author(s):  
V. Vesterinen ◽  
S. Ruffieux ◽  
A. Kalaboukhov ◽  
H. Sipola ◽  
M. Kiviranta ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Kinetic Inductance ◽  
High Tc ◽  
High Tc Superconductor ◽  
Field Sensing ◽  
Magnetic Field Sensing

scholarly journals Effect of Aerosil and Oleic Acid on Sedimentation of Magnetorheological Fluid

2019 ◽  
Vol 8 (12S2) ◽  
pp. 79-83
Keyword(s):  
Magnetic Field ◽  
Oleic Acid ◽  
Magnetic Force ◽  
Particle Concentration ◽  
Nano Particles ◽  
Carrier Fluid ◽  
Flux Lines ◽  
Smart Fluids ◽  
Magnetic Flux Lines ◽  
Ferro Magnetic

Magnetorheological Fluids (MRFs) are considered as smart fluids because they control viscosity using external magnetic field. It contains ferro-magnetic powder which are aligned in magnetic flux lines. The magnetic force between particles are controlled by magnetic field intensity. This controllable viscosity makes them acceptable in many mechanical applications, but due to difference in density between suspended particles and carrier fluid sedimentation is bound to occur. This thus creates the need of some additives. In our study, silica Nano particles (commercially known as Aerosil 200) is used as stabilizer and Oleic Acid is used as surfactant and their effect on sedimentation is studied in this article. Some other synthesis parameters like particle concentration, stirring duration and material loading also cause some change in sedimentation rate.

scholarly journals Flux Penetration Effects in High-Tc SQUIDs

1989 ◽  
Vol 42 (4) ◽  
pp. 401
Author(s):  
GJ SIoggett ◽  
lK Harvey ◽  
L Wieczorek ◽  
RE Binks ◽  
R Driver
Keyword(s):  
Magnetic Field ◽  
Copper Oxide ◽  
Direct Measurement ◽  
Barium Copper Oxide ◽  
Break Junction ◽  
Flux Penetration ◽  
High Tc ◽  
Bulk Ybco ◽  
Barium Copper ◽  
Yttrium Barium

Two experiments pertaining to the effects of intergranular flux penetration in high-Tc yttrium-barium-copper oxide (YBCO) SQUIDs are described. The first is a direct measurement of the flux noise of bulk YBCO exposed to the earth's magnetic field, and the second involves the fabrication and testing of break junction d.c. SQUIDs. Implications of a number of undesirable effects seen in these experiments are discussed.

Devonian magnetostratigraphy: new data and old problems

2021 ◽  
Author(s):  
Annique van der Boon ◽  
Andy Biggin ◽  
Daniele Thallner ◽  
Mark Hounslow ◽  
Jerzy Nawrocki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Time Scale ◽  
Age Determination ◽  
Paleomagnetic Data ◽  
Show Evidence ◽  
Reversal Frequency ◽  
Geomagnetic Polarity ◽  
Geomagnetic Polarity Time Scale

<p>The global polarity time scale (GPTS) is relatively unconstrained for the Paleozoic, particularly the Devonian. Constraining the GPTS and reversal frequency for the Devonian is crucial for the understanding of the behaviour of Earth’s magnetic field. Furthermore, construction of a GPTS for the Paleozoic could provide a valuable tool for age determination in other studies. However, most paleomagnetic data from the Devonian is problematic. The data are difficult to interpret and don’t have a single easy to resolve (partial or full) overprint. Paleointensity studies suggest that the field was much weaker than the field of today, which could have been accompanied by many reversals (a hyperreversing field). In order to improve the geomagnetic polarity time scale in the Devonian, and quantify the number of reversals in this time, we sampled three Devonian sections in Germany, Poland and Canada. These sections show evidence that the rocks were not significantly heated, and they show little evidence for remineralisation. This minimises the chance the rocks were remagnetised after the Devonian. Our data show that even when rocks are well qualified to have reliably recorded the Devonian field, the interpretation is not straightforward. We also discuss problems with the Devonian GPTS as presented in the geologic timescale.</p>

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