Irreversibility Effects and Low Field Magnetovoltage Measurements in Superconducting MgB2 Near the Critical Temperature T c

Olutaş, Murat; Kiliç, A.; Kılıç, Kıvılcım; Altinkok, A.

doi:10.1007/s10948-013-2201-9

Cited by 10 publications

(6 citation statements)

References 95 publications

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“…The physical origin of these effects is flux trapping in the intragranular and intergranular regions and is well understood [26][27][28][29]. Such measurements are reported for polycrystalline samples of high T c cuprate superconductors [31][32][33][34][35][36][37][38][39][40], BaPb- BiO [41], organic superconductors [42], M gB 2 [43,44], tungsten carbide [45], etc. Granularity can occur naturally in a polycrystalline sample due to the grain boundaries and can also be induced or enhanced by forming composites of the superconducting material and a nonsuperconducting material [26,[46][47][48][49][50].…”

Section: Granular Superconductorsmentioning

confidence: 99%

Granular Superconductivity in Hydrides Under Pressure

Hirsch

2022

J Supercond Nov Magn

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It has been suggested that the measured magnetic properties of hydrides under pressure claimed to be high temperature superconductors indicate that the materials are granular superconductors. Such materials will show reduced or no magnetic field expulsion under field cooling, and will trap magnetic fields when the external magnetic field is removed. They will also exhibit hysteretic behavior in magnetoresistance and other transport properties. Here we point out that hysteresis in transport properties has never been reported for hydrides under pressure. Its presence, with the expected features, would indicate that the materials trap magnetic flux, hence that they can sustain persistent currents without dissipation, something that all superconductors can do. Conversely, its absence would indicate that these materials are not superconductors.

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Section: Granular Superconductorsmentioning

confidence: 99%

Granular Superconductivity in Hydrides Under Pressure

Hirsch

2022

J Supercond Nov Magn

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“…Электросопротивление R измерялось четырехзондовым методом; размеры образца составляли 0.8×0.8×6 mm 3…”

Section: экспериментunclassified

“…Исследования магнитотранспортных свойств получаемых сверхпроводящих материалов являются неотъемлемой частью их характеризации [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Это касается как, ставших уже " классическими", гранулярных высокотемпературных сверхпроводников (ВТСП), так и новых, " гидридных" сверхпроводников [13,14].…”

Section: Introductionunclassified

Влияние Внутригранульных Мейсснеровских Токов И Захваченного В Гранулах Потока На Эффективное Поле В Межгранульной Среде И Гистерезис Магнитосопротивления Гранулярного ВТСП

Балаев¹,

Семенов²,

Гохфельд³

2022

Физика Твердого Тела

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The concept of an effective field in an intergranular medium is used to describe the hysteresis magnetoresistance of granular HTSCs. This effective field is a superposition of the external magnetic field and the field induced by the magnetic moments of the superconducting granules. The magnetic moment of the granules is contributed by the shielding currents and the trapped magnetic flux. We studied and analyzed the effect of the trapped flux on the magnetoresistance. It has been experimentally shown that the dependence of the residual resistance (after applying of the external field) on the trapped flux clearly correlates with the behavior of the remanent magnetization. In addition, special attention was paid to a detailed comparison of the magnetoresistance of the granular YBa2Cu3O7-delta for two cases: (a) the magnetization of HTSC granules is caused only by the trapped magnetic flux (in a zero external field) and (b) HTSC granules are in the Meissner state (the external field is smaller than the first critical field of the granules). It has been found that Abrikosov vortices and intragranular Meissner currents differently affect the effective field in the intergranular medium (for the same values of magnetization for cases (a) and (b)). A possible reason for this difference is discussed.

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“…Однако справедливость подобного тезиса далеко не очевидна, и вопрос о влиянии температуры и внеш-него магнитного поля на характер эволюции вихревой структуры гранулярных BCS-сверхпроводников MgB 2 окончательно не решен. Несмотря на огромное коли-чество работ, посвященных попыткам построения фазо-вых H−T -диаграмм гранулярных BCS-сверхпроводников MgB 2 при низких температурах (см., например, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]), до сих пор не установлено положение линий H c1g (H c1A ) и H c2J на фазовой H−T -диаграмме. Более того, подвергается сомнению и само существова-ние " слабых связей" [иными словами, наличие линии H c2J (T ) на H−T -диаграмме] в случае гранулярного BCS-сверхпроводника MgB 2 [22][23][24][25][26][27][28].…”

Section: G (T H) ≫ I J (T H)unclassified

Фазовые переходы в гранулярном BCS-сверхпроводнике MgB-=SUB=-2-=/SUB=- в слабых магнитных полях

Derevianko¹,

Sungurov²,

Sukhareva³

et al. 2017

Физика Твердого Тела

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Изучен характер температурных зависимостей электросопротивления гранулярных BCS-сверхпроводников MgB2 при ~35-45 K во внешних магнитных полях Hext напряженностью до ~2 kOe. Обнаружен эффект повышения ширины сверхпроводящего перехода Delta Tc при росте Hext. Установлено наличие системы "слабых связей" (weak links) в гранулярных сверхпроводниках на основе MgB2. На основании полученных экспериментальных данных установлена принадлежность гранулярного BCS-сверхпроводника MgB2 к двухуровневым сверхпроводящим системам, построена фазовая H-T-диаграмма. DOI: 10.21883/FTT.2017.02.44038.171

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Irreversibility Effects and Low Field Magnetovoltage Measurements in Superconducting MgB2 Near the Critical Temperature T c

Cited by 10 publications

References 95 publications

Granular Superconductivity in Hydrides Under Pressure

Granular Superconductivity in Hydrides Under Pressure

Фазовые переходы в гранулярном BCS-сверхпроводнике MgB-=SUB=-2-=/SUB=- в слабых магнитных полях

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