Self-organization of the critical state in granular superconductors

Ginzburg, S. L.; Savitskaya, N. E.

doi:10.1134/1.559076

Cited by 9 publications

(11 citation statements)

References 12 publications

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“…Interest in this material was significantly piqued by an apparent coexistence of superconductivity and ferromagnetism in high-quality samples (with very low residual resistivities of the order of 0.62 μΩ cm) [6]. Such coexistence, predicted decades ago by Ginzburg [7], was thought to be due to triplet pairing through spin fluctuations [8]. On the other hand, the Fulde-Ferrell-Larkin-Ovchinnikov state [9,10], influenced by the fermiology, was another candidate to explain this coexistence [11,12].…”

Section: Introductionmentioning

confidence: 98%

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂

2022

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The Fermi surface topology plays an important role in the macroscopic properties of metals. It can be particularly sensitive to electron correlation, which appears to be especially significant for the weak itinerant ferromagnet ZrZn2. Here, we look at the differences in the predicted Fermi surface sheets of this metallic compound in its paramagnetic phase for both density functional theory (DFT) and the combination of DFT with dynamical mean field theory (DFT+DMFT). The theoretical spectral functions evaluated at the Fermi level were used along with calculations of the electron-positron momentum density (also known as the two-photon momenutm density) in k-space to provide insights into the origin of certain features of the Fermi surface topology. We compare this two photon momentum density to that extracted from the positron annihilation experimental data (Phys.Rev.Lett.92,107003 (2004)). The DFT+DMFT densities are in better agreement with the experiment than the DFT, particularly with regard to the flat bands around the L and W high symmetry points. The experimental neck around L, which relates to a van Hove singularity, is present in DFT+DMFT but not in the DFT. We find that these flat bands, and as such the Fermi surface topology, are sensitive to the many body electron correlation description, and show that the positron annihilation technique is able to probe this. This description is significant for the observed behavior such as the Lifshiftz transition around the quantum critical point.

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Section: Introductionmentioning

confidence: 98%

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂

2022

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“…where ρ ≡ N/V = N c /V c is spin density. Expressions ( 30) and ( 31) were, first, found by Ginzburg [30], who used a classical picture, which also was discussed in [4,31]. Here we have presented a fully quantummechanical derivation of these expressions and, in addition, have obtained their generalizations ( 26), (27), and (29).…”

Section: Electromagnetic Spin Interactionsmentioning

confidence: 64%

Absence of spin superradiance in resonatorless magnets

Yukalov¹,

Yukalova²

2004

Laser Phys. Lett.

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A spin system is considered with a Hamiltonian typical of molecular magnets, having dipole-dipole interactions and a single-site magnetic anisotropy. In addition, spin interactions through the common radiation field are included. A fully quantummechanical derivation of the collective radiation rate is presented. An effective narrowing of the dipole-dipole attenuation, due to high spin polarization is taken into account. The influence of the radiation rate on spin dynamics is carefully analysed. It is shown that this influence is completely negligible. No noticeable collective effects, such as superradiance, can appear in molecular magnets, being caused by electromagnetic spin radiation. Spin superradiance can arise in molecular magnets only when these are coupled to a resonant electric circuit, as has been suggested earlier by one of the authors in Laser Phys. 12, 1089Phys. 12, (2002.

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“…When describing the magnetic and electric transport properties of PSs, the model of a two-level superconductor is used [42][43][44][45][46][47][48]. Inhomogeneous and polycrystalline superconductors are considered in the model as a Josephson medium [49][50][51] consisting of superconducting regions and weak links between them. The subsystem of weak links is responsible for the dissipation of energy in weak magnetic fields, while dissipation in strong magnetic fields occurs in the subsystem of superconducting regions.…”

Section: Trajectories Of Current In Porous Superconductorsmentioning

confidence: 99%

Highly Porous Superconductors: Synthesis, Research, and Prospects

Gokhfeld

Koblischka

Koblischka-Veneva

2020

Phys. Metals Metallogr.

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This paper gives a review of studies of superconductors with a porosity above 50%. The pores in such superconducting materials provide refrigerant penetration, efficient heat dissipation and stable operation. Methods for the synthesis of the main groups of porous superconductors are described. The results of studies of the structural, magnetic, and electrical transport properties are presented, and the features of the current flow through porous superconductors of various types are considered.

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Self-organization of the critical state in granular superconductors

Cited by 9 publications

References 12 publications

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂

Absence of spin superradiance in resonatorless magnets

Highly Porous Superconductors: Synthesis, Research, and Prospects

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Self-organization of the critical state in granular superconductors

Cited by 9 publications

References 12 publications

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn2

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn2

Absence of spin superradiance in resonatorless magnets

Highly Porous Superconductors: Synthesis, Research, and Prospects

Contact Info

Product

Resources

About

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂

Local electron correlation effects on the fermiology of the weak itinerant ferromagnet ZrZn₂