The rotational magnetic process and effects of gamma-irradiation on vortex flux pinning in Tl-2223 at low temperatures

Abstract

Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superconductor in fixed fields at low temperatures. Demonstrating the broad distribution in the vortex flux pinning, the vortex flux density B was seen to consist of two component: the rotational component BR turns rigidly with sample rotation and the frictional component BF stays at fixed angle F relative to the applied field H. The pinning torques per vortex were calculated as a function of H at constant temperature. The -irradiated sample shows an increase in pinning torque of ratio seven to one at temperatures 4.2 K and 25 K compared to an unirradiated sample; this is due to defects induced by the gamma irradiation.

Irreversible magnetization under rotating fields and lock-in effect on a ErBa2Cu3O7-δ single crystal with columnar defects

“…[12][13][14][15][16][17][18] If this effect were significant, as the rotation proceeded the orientation of the vortices would lag behind the field direction. In an extreme case, vortices deep inside the sample would rotate rigidly with it, a situation that has indeed been observed [19][20][21] . As we will show below, in the present case we have clear experimental evidence that the misorientation between the vortex direction and H due to this lag effect is negligible, so all this complication can be ignored.…”

Sensitivity of YBa2Cu3O7 thick films to gamma rays

“…For example, Umezawa et al [2] reported an enhancement of the magnitude and reduction of anisotropy of the magnetization current density with slight decrease in the transition temperature in YBCO single crystal due to fast neutron irradiation. Hasan et al [4] observed a considerable increase in the vortex flux pinning in Tl-2223 polycrystals with gamma radiation. Using heavy ion irradiation, Hillmer et al [5] produced columnar defects of different densities and orientations in epitaxial Bi-2212 thin film that increase the normal state resistance and decrease the transition temperature.…”

Влияние Радиационных Дефектов Различного Типа На Критический Ток Слоистого Анизотропного Сверхпроводника

“…Таким образом, излучение влияет на магнитные и транспортные свойства сверхпроводника, и это также означает возможность изменять свойства образца, целенаправленно облучая его частицами различного типа. На практике используется облучение нейтронами [1], протонами [2], электронами [3], γ-квантами [4] и тяжелыми ионами [5]. При этом форма дефекта зависит от энергии и типа облучающих частиц.…”