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Journal Articles

Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Semboshi, Satoshi*; Ozaki, Toshinori*; Sakane, Hitoshi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito

Japanese Journal of Applied Physics, 59(2), p.023001_1 - 023001_7, 2020/02

 Times Cited Count:1 Percentile:52.74(Physics, Applied)

We show that Xe ion irradiation with 80 MeV to GdBa$$_{2}$$Cu$$_{3}$$Oy-coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles relative to the c-axis: continuous CDs with a larger diameter are formed for oblique irradiation at $$theta_{rm i}$$ = 45$$^{circ}$$, whereas the same ion beam at a different angle ($$theta_{rm i}$$ = 0$$^{circ}$$) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density $$J_{rm c}$$.

Journal Articles

Flux pinning properties in YBCO films with growth-controlled nano-dots and heavy-ion irradiation defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 530, p.72 - 75, 2016/11

 Times Cited Count:5 Percentile:65.32(Physics, Applied)

In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the $$c$$-axis direction into quasi-multilayered films consisting of YBa$$_{2}$$Cu$$_{3}$$Oy layers and pseudo layers of BaSnO$$_{3}$$. The positive effect of the BaSnO$$_{3}$$ doping on the hybrid flux pinning stands out for the critical current density $$J_{rm c}$$ around $$B parallel c$$ in high magnetic field and/or inclined magnetic field off the $$c$$-axis, whereas there is little difference in the $$J_{rm c}$$ at $$B parallel c$$ among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO$$_{3}$$ nano-dots, the Jc around $$B parallel ab$$ is remarkably enhanced, whereas there is a detrimental effect on the Jc around $$B parallel c$$. These imply that the tuning of 3D-PCs is one of the keys to improve the $$J_{rm c}$$ at all magnetic field orientations for the hybrid flux pinning.

Journal Articles

High flux pinning efficiency by columnar defects dispersed in three directions in YBCO thin films

Sueyoshi, Tetsuro*; Nishimura, Takahiro*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Superconductor Science and Technology, 29(10), p.105006_1 - 105006_7, 2016/10

 Times Cited Count:6 Percentile:60.05(Physics, Applied)

A systematic investigation of flux pinning by widely direction-dispersed columnar defects (CDs) in YBa$$_{2}$$Cu$$_{3}$$Oy thin films was carried out by using heavy-ion irradiation: a parallel configuration of CDs aligned along the $$c$$-axis, and two trimodal splay configurations composed of crossing CDs; relative to the $$c$$-axis, where the splay plane defined by the three irradiation angles is perpendicular (trimodal-A) or parallel (trimodal-B) to the transport current direction. The trimodal configurations show high pinning efficiency over a wide range of magnetic field orientations compared to the parallel one at low magnetic field. In particular, trimodal-B shows the higher critical current density of the two trimodal configurations.

Journal Articles

Flux pinning properties in GdBCO coated conductors containing columnar defects with splay plane parallel to current direction

Furuki, Yuichi*; Sueyoshi, Tetsuro*; Kai, Takashi*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 518, p.58 - 62, 2015/11

 Times Cited Count:4 Percentile:81.03(Physics, Applied)

In order to reveal the influence of crossing angle of one-dimensional pinning centers on angular dependence of critical current density Jc, heavy-ion irradiation was performed to introduce columnar defects (CDs) crossing relative to the c-axis into GdBCO coated conductors, where the splay plane consisting of the two directions of CDs is parallel to the current flow direction. For the sample containing CDs with 15$$^{circ}$$, a single and sharp peak was observed around B$$||$$c in the angular dependence of Jc. When the crossing angle was extended to 45$$^{circ}$$, the single Jc-peak became broader, which was a gently-sloping mountain-like shape centered at B$$||$$c. For 75$$^{circ}$$, on the other hand, a quite different behaviour of Jc from the other irradiated samples was observed, which was analogous to the angular dependence of Jc typical of three dimensional pinning centers.

Journal Articles

Influence of discontinuous columnar defects on flux pinning properties in GdBCO coated conductors

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06

 Times Cited Count:6 Percentile:58(Engineering, Electrical & Electronic)

To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.

Journal Articles

Angular dependence of critical current density and $$n$$-values in BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ quasi-multilayered films with columnar defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Physica C, 494, p.153 - 157, 2013/11

 Times Cited Count:5 Percentile:70.57(Physics, Applied)

BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$Oy quasi-multilayered films, in which the size and the spatial distribution of BaZrO$$_{3}$$ nano-particles were controlled, were irradiated using 200 MeV Xe ions along the c-axis direction. Whenthe BaZrO$$_{3}$$ nano-particles were larger in size, the flux lines not captured by CDs, such as interstitial fluxlines between CDs and double kinks of flux lines, can be pinned more effectively by the BaZrO$$_{3}$$ nano-particles, so that the Jc enhances for high magnetic fields and high temperature. In addition, the inverse correlation between Jc and n-value appears at high temperature in increasing magnetic field for the film with correlated rows of the nano-particles which might be curved off the c-axis. These suggest that the hybrid flux pinning depends not only on the combination of one-dimensional (1D) and three-dimensional pinning centers (3D-PCs) but also on the size and the spatial distribution of the 3D-PCs.

Journal Articles

Angular dependence of critical current density in YBCO films with columnar defects crossing at widespread angles

Sueyoshi, Tetsuro*; Furuki, Yuichi*; Tanaka, Eiki*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 23(3), p.8002404_1 - 8002404_4, 2013/06

 Times Cited Count:7 Percentile:56.28(Engineering, Electrical & Electronic)

To investigate whether one dimensional pinning centers (1D PCs) can attain the isotropic critical current density ($$J_{c}$$) properties, columnar defects (CDs) crossing at widespread angles were installed by heavy-ion irradiations into YBCO thin films. For the sample containing the CDs crossing relative to the $$c$$-axis, the plateau-like behavior of $$J$$$$_{c}$$ is realized over a wide range of magnetic field orientations, except for around B $$||$$ $$ab$$-plane where a dip structure is accompanied by a rapid decline of the $$J_{c}$$. For the bimodal splay configuration consisting of CDs crossing relative to the $$c$$-axis, a single peak around the $$c$$-axis is observed in the angular dependence of $$J_{c}$$, suggesting the splay effect at B $$||$$ $$c$$-axis by the crossed CDs. Two parallel families of CDs crossing relative to the $$ab$$-plane, on the other hand, bring about not a peak but a dip around B $$||$$ $$ab$$-plane on the angular dependence of $$J_{c}$$.

Journal Articles

Critical current density of YBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ containing inclined columnar defects

Ishikawa, Norito; Sueyoshi, Tetsuro*; Iwase, Akihiro; Chimi, Yasuhiro; Fujiyoshi, Takanori*; Miyahara, K.*; Kisu, T.*

Physica C, 357-360(Part.1), p.505 - 508, 2001/09

no abstracts in English

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