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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：9 Percentile：37.29(Physics, Applied)We show that Xe ion irradiation with 80 MeV to GdBa
Cu
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 
= 45
, whereas the same ion beam at a different angle ( = 0) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density 
.
Furuki, Yuichi*; Sueyoshi, Tetsuro*; Kai, Takashi*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Ishikawa, Norito
Physica C, 518, p.58 - 62, 2015/11
Times Cited Count：6 Percentile：24.96(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, a single and sharp peak was observed around B
c in the angular dependence of Jc. When the crossing angle was extended to 45, the single Jc-peak became broader, which was a gently-sloping mountain-like shape centered at Bc. For 75, 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.
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：12 Percentile：49.19(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.
-axis to 
-plane in GdBCO coated conductorsSueyoshi, Tetsuro*; Furuki, Yuichi*; Kai, Takashi*; Fujiyoshi, Takanori*; Ishikawa, Norito
Physica C, 504, p.53 - 56, 2014/09
Times Cited Count：10 Percentile：38.14(Physics, Applied)GdBaCuO
(GdBCO) coated conductors were irradiated using 270 MeV Xe ions at crossing angles 
relative to the -axis, in order to clarify the flux pinning properties of splayed columnar defects (splayed CDs) not only around 
-axis, but also around -plane. For the splayed CDs with smaller (i.e. crossing around the -axis), a single peak is observed around -plane in the angular dependence of critical current density , which are attributed to the splay effect by the crossed CDs. For the splayed CDs with larger (i.e. crossing around the -plane), on the other hand, two sharp peaks emerge near two irradiation angles and the at -plane indicates not a peak but a dip structure.
Sueyoshi, Tetsuro*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito
Teion Kogaku, 49(3), p.139 - 144, 2014/03
Columnar defects (CDs) produced by heavy-ion irradiations in high-Tc superconductors such as YBaCuOy (YBCO) are the most effective pinning centers to immobilize flux lines, leading to the enhancement of critical current density Jc. In addition, slight dispersion (splay) in directions of CDs can further improve the Jc. In this work, YBCO thin films were irradiated using 200 MeV Xe ions at two angles relative to the c-axis in two geometries where the direction of current is perpendicular (mode A) or parallel to the splay plane (mode B), to investigate the influence of the direction of splay plane on the flux pinning properties.
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：9 Percentile：42.74(Engineering, Electrical & Electronic)To investigate whether one dimensional pinning centers (1D PCs) can attain the isotropic critical current density (
) 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 -axis, the plateau-like behavior of 
is realized over a wide range of magnetic field orientations, except for around B -plane where a dip structure is accompanied by a rapid decline of the . For the bimodal splay configuration consisting of CDs crossing relative to the -axis, a single peak around the -axis is observed in the angular dependence of , suggesting the splay effect at B -axis by the crossed CDs. Two parallel families of CDs crossing relative to the -plane, on the other hand, bring about not a peak but a dip around B -plane on the angular dependence of .
