TY - JOUR
T1 - Properties of MgB2 films with very high transport critical current densities
AU - Kitaguchi, Hitoshi
AU - Doi, Toshiya
AU - Kobayashi, Yuki
AU - Matsumoto, Akiyoshi
AU - Sosiati, Harini
AU - Hata, Satoshi
AU - Fukutomi, Masao
AU - Kumakura, Hiroaki
N1 - Funding Information:
Manuscript received October 4, 2004. This work was supported in part by Research Promotion Bureau, Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, under contract 16-556. TEM analyses were carried in “Nanotechnology Support Project” of the MEXT, Japan. H. Kitaguchi, A. Matsumoto, M. Fukutomi, and H. Kumakura are with the Oxide Superconducting Wires Group, Superconducting Materials Center (SMC), National Institute for Materials Science (NIMS), Tsukuba, Japan (e-mail: KITAGUCHI.Hitoshi@nims.go.jp). T. Doi and Y. Kobayashi are with Kagoshima University, Kagoshima, Japan. H. Sosiati and S. Hata are with Kyushu University, Fukuoka, Japan. Digital Object Identifier 10.1109/TASC.2005.848866
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005/6
Y1 - 2005/6
N2 - Magnesium diboride, MgB2, thin films are fabricated through two different kinds of process. One is an in-situ process by using electron beam deposition and the other is an ex-situ process by using the combination of pulsed laser deposition and heat treatment. The critical current density, J c, is investigated as a function of external magnetic field in the range of 0-7 T and/or temperatures ranging from 4.2 K to the critical temperature by using dc 4-probe transport method. The in-situ processed film shows very high Jc, e.g., 7.1×106, 1.2×10 6, and 1.4×105 A/cm2 in 0, 4, and 7 T (perpendicular fields), respectively. Angular dependence of Jc is much different between the two kinds of films. Jc-angle (magnetic field) curves of the in-situ processed film show two peaks; one is around the field perpendicular to the film surface and the other is around the parallel field. On the contrary, the curves of the ex-situ processed film have only one peak around the parallel field. Microstructure analyses show that the in-situ film has columnar grains aligned perpendicular to the film surface and that the ex-situ one has granular grains with random orientations. These results indicate that the grain boundaries between columnar grains act as effective pinning centers and enhance Jc in the perpendicular fields.
AB - Magnesium diboride, MgB2, thin films are fabricated through two different kinds of process. One is an in-situ process by using electron beam deposition and the other is an ex-situ process by using the combination of pulsed laser deposition and heat treatment. The critical current density, J c, is investigated as a function of external magnetic field in the range of 0-7 T and/or temperatures ranging from 4.2 K to the critical temperature by using dc 4-probe transport method. The in-situ processed film shows very high Jc, e.g., 7.1×106, 1.2×10 6, and 1.4×105 A/cm2 in 0, 4, and 7 T (perpendicular fields), respectively. Angular dependence of Jc is much different between the two kinds of films. Jc-angle (magnetic field) curves of the in-situ processed film show two peaks; one is around the field perpendicular to the film surface and the other is around the parallel field. On the contrary, the curves of the ex-situ processed film have only one peak around the parallel field. Microstructure analyses show that the in-situ film has columnar grains aligned perpendicular to the film surface and that the ex-situ one has granular grains with random orientations. These results indicate that the grain boundaries between columnar grains act as effective pinning centers and enhance Jc in the perpendicular fields.
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U2 - 10.1109/TASC.2005.848866
DO - 10.1109/TASC.2005.848866
M3 - Article
AN - SCOPUS:22144477162
VL - 15
SP - 3313
EP - 3316
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
SN - 1051-8223
IS - 2 PART III
ER -