Hysteresis of the magnetoresistance of granular HTSC YBa2Cu3O7 − δ in weak fields

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

doi:10.1134/s1063783408060012

Cited by 22 publications

(8 citation statements)

References 18 publications

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“…As was expected (see Introduction), the obtained experimental data, which are not principally different from the published results of studying CVCs of YBCO samples (see, e.g., [24][25][26][27][28][29][30][31][32][33][34][35]) and even reveal some sig nificant changes in shapes of the and curves, provide no sufficient grounds for selecting one of the two alternative models of evolu tion of the subsystem of weak links. According to these models, there can be either one or several types of…”

Section: Results Of the Investigationcontrasting

confidence: 52%

“…[13,[24][25][26][27][28][29][30][31][32][33][34][35]) by a strong depen dence of the critical Josephson current density j cJ on the external magnetic field H ext . We have studied the dynamics of CVC variation for granular HTSCs in "very weak" (in terms of [36]) external magnetic fields (H ext from 0 up to about 18 Oe) at liquid nitrogen boil ing temperature (T = 77.3 K).…”

Section: T V Sukhareva and V A Finkel*mentioning

confidence: 98%

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Peculiarities in galvanomagnetic properties of granular YBa2Cu3O7−δ high-temperature superconductors in very weak magnetic fields

Sukhareva

Finkel

2012

Phys. Solid State

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The character of the evolution of a system of weak links in granular high temperature supercon ductors under the action of an external magnetic field H ext has been studied by measuring the current-voltage characteristics of YBa 2 Cu 3 O 7 -δ (δ ≈ 0.05) ceramic samples. The measurements have been performed at T = 77.3 K in a range of very weak magnetic fields 0 < H ext Շ 0.5H c2J , where H c2J is the upper critical field of the Josephson weak links. The results have been used to construct the field dependences of the magnetoresistance Δρ(H ext ) of the superconducting ceramics. It has been established that the parameters of the power equation E = A( j -j cJ ) ν and the magnetoresistance Δρ are nonmonotonic functions of the external magnetic field. The presence of extrema in the curves A(H ext ), j cJ (H ext ), ν(H ext ), and Δρ(H ext ) indicates that different systems of weak links between grain boundaries, which are capable of forming extended Josephson contacts, undergo sequential transitions to a resistive state with an increase in H ext .

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Section: Results Of the Investigationcontrasting

confidence: 52%

Section: T V Sukhareva and V A Finkel*mentioning

confidence: 98%

Peculiarities in galvanomagnetic properties of granular YBa2Cu3O7−δ high-temperature superconductors in very weak magnetic fields

Sukhareva

Finkel

2012

Phys. Solid State

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“…Note that the hysteresis of magnetoresistance was usually observed in granular systems, but in contrast to our results obtained in a single-crystal FeSe, it contained non-reversible values of the resistance during reversible magnetizing. This gave rise to interpret its nature in terms of percolation mechanism of current flow along the network of Josephson junctions [27]. The data from our single-crystal samples of FeSe rejecting such a possibility are closest to a vortex scenario of hysteresis which is based on the dissipative mechanism of synchronizing the vortices in the presence of defects [28].…”

Section: Resultsmentioning

confidence: 71%

Study of the itinerant electron magnetism of Fe-based superconductors by the proximity effect

Chiang¹,

Чареев²,

Dzuba³

et al. 2013

Physica C: Superconductivity

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We used the proximity effect as a tool to achieve an ideal ("barrier-free") NS boundary for quantitative evaluation of transport phenomena that accompany converting dissipative current into supercurrent in NS systems with unconventional superconductors -single-crystal chalcogenide FeSe and granulated pnictide LaO(F)FeAs. Using features (limitations) of Andreev reflection in the NS systems with dispersion of the electron spin subbands, we revealed direct evidence for spin-polarized nature of transport and the absence of residual magnetization in iron-based superconductors in the normal state: In heterocontacts with single-crystal FeSe and granular LaO(F)FeAs, we detected a spin-dependent contribution to the efficiency of the Andreev reflection associated with the spin accumulation at the NS boundary, and a hysteresis of conductivity of FeSe in the ground state in low external magnetic fields. Based on our findings, we conclude that in iron-based superconductors, the itinerant electron magnetism is predominant, magnetism of iron atoms being localized.

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“…(iii) The magnetoresistance anisotropy with respect to the mutual orientation of the external field and macroscopic transport current j; in this case, we have R(H || j) < R(H ⊥ j) [36,37,[48][49][50][51][52] and the R(H) hysteresis is broader at the perpendicular orientation H ⊥ j [53][54][55].…”

Section: Introductionmentioning

confidence: 96%

“…Indeed, there is a set of experimental facts that cannot be explained in the framework of the conventional approach. These facts include the following: (i) A fairly complex shape of the R(H) hysteresis [29][30][31][32][33][34][35][36][37][38][39][40][41][42] and J C (H) [43][44][45][46][47]; in this case, we have R(H inc ) > R(H dec ) and J C (H inc ) < J C (H dec ) under cycling of the external field to some constant value ±H max (hereinafter, the subscripts inc and dec are referred to the increasing and decreasing external fields, respectively), although, in the initial magnetoresistance branch R(H ini ) in relatively weak external field, the situation is opposite: R(H ini ) < R(H dec ).…”

Section: Introductionmentioning

confidence: 99%

Universal Behavior and Temperature Evolution of the Magnetoresistance Hysteresis in Granular High-Temperature Superconductors Y–Ba–Cu–O

2021

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Regularities in the behavior of the magnetoresistance hysteresis R(H) in the granular yttrium hightemperature superconductors (HTSs) have been established. For this purpose, a comparative analysis of the magnetotransport properties has been carried out on the granular HTS samples, which exhibit (i) approximately the same magnetic properties and temperatures of the onset of the superconducting transition (90.5-93.5 K, which is characteristic of HTS grains) and (ii) different critical transport currents J C (which is characteristic of grain boundaries). Despite a significant (by more than an order of magnitude) spread of the J C values for the three samples, a universal behavior of the magnetoresistance hysteresis has been found, which is apparently inherent in all the granular Y-Ba-Cu-O compounds. The R(H) hysteresis is extremely broad and, in a fairly wide external field range, the dependence of the magnetoresistance hysteresis width ΔН on the field H dec (the external field for the decreasing hysteresis branch is Н = H dec ) is almost linear: ΔH ≈ H dec . This behavior is observed over the entire temperature range of implementation of the superconducting state (the investigations have been carried out at temperatures of 77-88 and 4.2 K). The result obtained has been explained by considering the effective field in grain boundaries, which is a superposition of the external field and the field induced by the magnetic moments of grains. The field induced by grains, in turn, significantly increases in the region of grain boundaries due to the magnetic flux compression (the grain boundary length is shorter than the HTS grain size by several orders of magnitude). The aforesaid has been confirmed by the analysis of the R(H) hysteresis for the Y-Ba-Cu-O-and CuO-based HTS composite, in which the grain boundary length is purposefully increased; as a result, the flux compression is less pronounced and the R(H) hysteresis narrows.

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Hysteresis of the magnetoresistance of granular HTSC YBa2Cu3O7 − δ in weak fields

Cited by 22 publications

References 18 publications

Peculiarities in galvanomagnetic properties of granular YBa2Cu3O7−δ high-temperature superconductors in very weak magnetic fields

Peculiarities in galvanomagnetic properties of granular YBa2Cu3O7−δ high-temperature superconductors in very weak magnetic fields

Study of the itinerant electron magnetism of Fe-based superconductors by the proximity effect

Universal Behavior and Temperature Evolution of the Magnetoresistance Hysteresis in Granular High-Temperature Superconductors Y–Ba–Cu–O

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