Phase transitions and vortex structure evolution in two-level high-temperature granular superconductor YBa2Cu3O7 – δ under temperature and magnetic field

Derevyanko, V. V.; Sukhareva, T. V.; Finkel, V. A.

doi:10.1134/s1063783417080091

Cited by 14 publications

(1 citation statement)

References 44 publications

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“…Figure 1 demonstrates that the curve computed with a bell-shaped f peak (B) function (the Gauss function) and the curve computed with the logistic function are quite similar. The logistic function is a part of a Boltzmann sigmoid function, which is typically used to describe crossovers between phases [15][16][17][18] . The Boltzmann sigmoid function is written as…”

Section: Introductionmentioning

confidence: 99%

Use of a Sigmoid Function to Describe Second Peak in Magnetization Loops

Gokhfeld

2017

J Supercond Nov Magn

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Order-disorder transitions of a vortex lattice transfer type-II superconductors from a low critical current state to a high one. The similar transition between different current states can be caused by electromagnetic granularity. A sigmoid curve is proposed to describe the corresponding peak in a field dependence of the macroscopic critical density. Using the extended critical state model, analytic expressions are obtained for the field dependencies of the local critical current density, the depth of equilibrium surface region, and the macroscopic critical current density. The expressions are well fit to published data.

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Section: Introductionmentioning

confidence: 99%

Use of a Sigmoid Function to Describe Second Peak in Magnetization Loops

Gokhfeld

2017

J Supercond Nov Magn

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New model to predict thermomagnetic properties of nanostructured magnetic compounds

Gokhfeld,

Koblischka,

Koblischka-Veneva

2024

Appl. Phys. A

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The development of new materials showing the magneto-caloric effect (MCE) requires fast and reliable characterization methods. For this purpose, a phenomenological model developed by M. A. Hamad has proven to be a useful tool to predict the magnetocaloric properties (the isothermal magnetic entropy change, $$\Delta S_\textrm{M}$$ Δ S M , the magnetization-related change of the specific heat, $$\Delta C_{P,H}$$ Δ C P , H , and the relative cooling power, RCP) via calculation from magnetization measurements as a function of temperature, M(T). However, fitting the M(T) data is difficult for broad, smoothed-out transition curves which are often observed for material systems such as core-shell nanoparticles, nanowires, nanowire fabrics or nanoparticle hybrid materials. Thus, in this contribution we present a different approach enabling proper fitting of such magnetization data via the use of an asymmetric Boltzmann sigmoid function, which provides a clear physical background and enables to properly describe the broad and smoothed out transitions of nanomaterials. As examples for our procedure, we present fits to M(T) curves of polycrystalline, bulk $$\hbox {La}_{0.67}\hbox {Ba}_{0.33}\hbox {MnO}_3$$ La 0.67 Ba 0.33 MnO 3 as well as $$\hbox {La}_{1-x}\hbox {Sr}_{x}\hbox {MnO}_3$$ La 1 - x Sr x MnO 3 ($$x=$$ x = 0.2, 0.3, 0.4) and $$\hbox {La}_{0.7}\hbox {Ca}_{0.3}\hbox {MnO}_3$$ La 0.7 Ca 0.3 MnO 3 nanostructured materials from various authors.

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