scholarly journals Gaussian and critical scalings in the magnetoconductivity fluctuations of Y3Ba5Cu8O18 superconductor

2018 ◽  
Vol 32 (32) ◽  
pp. 1850360
Author(s):  
F. T. Dias ◽  
V. N. Vieira ◽  
C. P. Oliveira ◽  
D. L. Silva ◽  
F. Mesquita ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Power Law ◽  
Applied Magnetic Field ◽  
Granular Structure ◽  
Superconducting Transition ◽  
Critical Scaling ◽  
First Order ◽  
Zero Resistance

We have studied the superconducting transition and the magnetoconductivity fluctuations in the polycrystalline Y3Ba5Cu8O[Formula: see text] (Y358) superconductor under magnetic fields upto 1 T. A two-step superconducting transition could be observed as a consequence of the granular structure of the sample, which is strongly affected by the applied magnetic field. Gaussian and genuine critical 3D-XY-E fluctuation regimes were identified. A critical scaling regime beyond 3D-XY was identified for magnetic fields upto 0.25 T, corresponding to the averaged exponent 0.19 and suggesting the occurrence of the weak first-order character of the superconducting transition. In the approximation to the zero resistance a power law regime could be observed, corresponding to the averaged exponent 2.37, which are smaller than previously reported for the Y358 system. Our results are discussed in terms of the Y358 and YBa2Cu3O[Formula: see text](Y123) results in the literature.

THERMAL EXPANSION AND MAGNETOSTRICTION OF THE HEAVY-FERMION COMPOUND UPd2Al3

1993 ◽  
Vol 07 (01n03) ◽  
pp. 42-45 ◽  
Author(s):  
R. MODLER ◽  
K. GLOOS ◽  
C. GEIBEL ◽  
T. KOMATSUBARA ◽  
N. SATO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Expansion ◽  
Magnetic Fields ◽  
Applied Magnetic Field ◽  
Heavy Fermion ◽  
First Order ◽  
Magnetic Superconductor ◽  
Magnetic Effects ◽  
Heavy Fermion Compound

We report on thermal expansion and magnetostriction of the new hexagonal heavy fermion magnetic superconductor UPd 2 Al 3. Measurements were taken on monocrystalline samples between 0.1K and 20K in magnetic fields up to 4T. Both thermal expansion and magnetostriction are strongly anisotropic and are dominated by magnetic effects. In an applied magnetic field, the thermal expansion anomaly observed near T c seems to be of first order.

scholarly journals Expansion of the high field-boosted superconductivity in UTe2 under pressure

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Sheng Ran ◽  
Shanta R. Saha ◽  
I-Lin Liu ◽  
David Graf ◽  
Johnpierre Paglione ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Field ◽  
Superconducting Phase ◽  
High Symmetry ◽  
First Order ◽  
Superconducting Phases ◽  
Quantum Phenomenon ◽  
Zero Resistance ◽  
Spin Triplet ◽  
The Magnetic Field

AbstractMagnetic field-induced superconductivity is a fascinating quantum phenomenon, whose origin is yet to be fully understood. The recently discovered spin-triplet superconductor, UTe2, exhibits two such superconducting phases, with the second one reentering in the magnetic field of 45 T and persisting up to 65 T. More surprisingly, in order to induce this superconducting phase, the magnetic field has to be applied in a special angle range, not along any high symmetry crystalline direction. Here we investigated the evolution of this high-field-induced superconducting phase under pressure. Two superconducting phases merge together under pressure, and the zero resistance persists up to 45 T, the field limit of the current study. We also reveal that the high-field-induced superconducting phase is completely decoupled from the first-order field-polarized phase transition, different from the previously known example of field-induced superconductivity in URhGe, indicating superconductivity boosted by a different paring mechanism.

scholarly journals Decaying turbulence and magnetic fields in galaxy clusters

2019 ◽  
Vol 488 (3) ◽  
pp. 3439-3445 ◽  
Author(s):  
Sharanya Sur
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Galaxy Clusters ◽  
Power Law ◽  
Dynamo Action ◽  
Wide Range ◽  
Major Merger ◽  
Decaying Turbulence ◽  
Field Decay ◽  
The Magnetic Field

Abstract We explore the decay of turbulence and magnetic fields generated by fluctuation dynamo action in the context of galaxy clusters where such a decaying phase can occur in the aftermath of a major merger event. Using idealized numerical simulations that start from a kinetically dominated regime we focus on the decay of the steady state rms velocity and the magnetic field for a wide range of conditions that include varying the compressibility of the flow, the forcing wavenumber, and the magnetic Prandtl number. Irrespective of the compressibility of the flow, both the rms velocity and the rms magnetic field decay as a power law in time. In the subsonic case we find that the exponent of the power law is consistent with the −3/5 scaling reported in previous studies. However, in the transonic regime both the rms velocity and the magnetic field initially undergo rapid decay with an ≈t−1.1 scaling with time. This is followed by a phase of slow decay where the decay of the rms velocity exhibits an ≈−3/5 scaling in time, while the rms magnetic field scales as ≈−5/7. Furthermore, analysis of the Faraday rotation measure (RM) reveals that the Faraday RM also decays as a power law in time ≈t−5/7; steeper than the ∼t−2/5 scaling obtained in previous simulations of magnetic field decay in subsonic turbulence. Apart from galaxy clusters, our work can have potential implications in the study of magnetic fields in elliptical galaxies.

scholarly journals Low-degree mixed modes in red giant stars with moderate core magnetic fields

2019 ◽  
Author(s):  
Shyeh Tjing Loi ◽  
John C B Papaloizou
Keyword(s):  
Magnetic Field ◽  
Perturbation Theory ◽  
Magnetic Fields ◽  
Differential Equations ◽  
Order Perturbation ◽  
First Order ◽  
Low Degree ◽  
Mixed Modes ◽  
The Magnetic Field ◽  
First Order Perturbation

Abstract Observations of pressure-gravity mixed modes, combined with a theoretical framework for understanding mode formation, can yield a wealth of information about deep stellar interiors. In this paper, we seek to develop a formalism for treating the effects of deeply buried core magnetic fields on mixed modes in evolved stars, where the fields are moderate, i.e. not strong enough to disrupt wave propagation, but where they may be too strong for non-degenerate first-order perturbation theory to be applied. The magnetic field is incorporated in a way that avoids having to use this. Inclusion of the Lorentz force term is shown to yield a system of differential equations that allows for the magnetically-affected eigenfunctions to be computed from scratch, rather than following the approach of first-order perturbation theory. For sufficiently weak fields, coupling between different spherical harmonics can be neglected, allowing for reduction to a second-order system of ordinary differential equations akin to the usual oscillation equations that can be solved analogously. We derive expressions for (i) the mixed-mode quantisation condition in the presence of a field and (ii) the frequency shift associated with the magnetic field. In addition, for modes of low degree we uncover an extra offset term in the quantisation condition that is sensitive to properties of the evanescent zone. These expressions may be inverted to extract information about the stellar structure and magnetic field from observational data.

On the structure of collisionless waves

1969 ◽  
Vol 3 (4) ◽  
pp. 673-689 ◽  
Author(s):  
James B. Fedele
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Small Amplitude ◽  
Single Mode ◽  
Larmor Radius ◽  
Collisionless Shock ◽  
Finite Larmor Radius ◽  
First Order ◽  
Pulse Solution ◽  
Solitary Pulse

Small amplitude waves and collisionless shock waves are investigated within the framework of the first-order Chew—Goldberger—Low equations. For linearized oscillations, two modes are present for propagation along an applied magnetic field. One is an acoustic type which contains no finite Larmor radius effects. The other which contains the ‘fire hose’ instability in its lowest order terms, does possess finite Larmor radius corrections. These corrections, however, do not produce instabilities or dissipation. There are no finite Larmor radius corrections to the single mode present for propagation normal to the applied magnetic field. Normal shock structure is investigated, but it is shown that jump solutions do not exist. An analytic solitary pulse solution is found and is compared with the Adlam—Allen pulse solution.

scholarly journals Пылевая плазма в тлеющем разряде в магнитном поле до 3000 G

2018 ◽  
Vol 44 (19) ◽  
pp. 66
Author(s):  
Е.С. Дзлиева ◽  
Л.А. Новиков ◽  
С.И. Павлов ◽  
В.Ю. Карасев
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Glow Discharge ◽  
Magnetic Fields ◽  
Dusty Plasma ◽  
Drag Force ◽  
Applied Magnetic Field ◽  
Magnetic Trap ◽  
Current Channel ◽  
Angular Velocities

AbstractA glow discharge dusty plasma in a magnetic trap in which the current channel narrows is obtained in moderate magnetic fields up to 3000 G. The results of initial experiments are reported. The formation of stable dusty plasma structures rotating at record-high angular velocities up to 15 rad/s is observed. The dependence of the angular velocity on the strength of the applied magnetic field is measured experimentally. We interpret it quantitatively on the basis of the ion drag force.

A COMPARISON OF RESISTANCE BROADENING IN MAGNETIC FIELD OF SINGLE CRYSTAL YBa2Cu3O7−δ AND THE ORGANIC SUPERCONDUCTOR κ-(BEDT-TTF)2Cu[N(CN)2]Br

1991 ◽  
Vol 05 (08) ◽  
pp. 547-554 ◽  
Author(s):  
W.K. KWOK
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Applied Magnetic Field ◽  
Organic Superconductor ◽  
High Magnetic Fields ◽  
Resistive Transition ◽  
Resistivity Measurements ◽  
Zero Resistance

AC resistivity measurements in fields up to 8 Tesla in fully oxygenated and oxygen deficient single crystals of YBa 2 Cu 3 O 7−δ are presented. Fully oxygenated crystals show the characteristic ‘fantail’ broadening in magnetic field where the onset temperature remains virtually independent of the applied magnetic field and the zero resistance temperature decreases dramatically. However, in oxygen deficient crystals, the temperature dependence of the resistivity undergoes a change in shape at high magnetic fields. These results are compared with the recently discovered highest Tc=11.6 K organic superconductor κ- (ET) 2 Cu[N(CN) 2] Br where the shape of the resistive transition for H||b undergoes a change from a ‘fantail’ resistive broadening in magnetic field to that of a more conventional low Tc superconductor.

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