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Full-Text Articles in Engineering
Self-Doping Effect And Successive Magnetic Transitions In Superconducting Sr2 Vfeaso3, Guanghan Cao, Zhifeng Ma, Cao Wang, Yunlei Sun, Jinke Bao, Shuai Jiang, Yi Luo, Chunmu Feng, Yi Zhou, Zhi Xie, Fengchun Hu, Shiqiang Wei, I Nowik, I Felner, Lei Zhang, Zhu-An Xu, Fu-Chun Zhang
Self-Doping Effect And Successive Magnetic Transitions In Superconducting Sr2 Vfeaso3, Guanghan Cao, Zhifeng Ma, Cao Wang, Yunlei Sun, Jinke Bao, Shuai Jiang, Yi Luo, Chunmu Feng, Yi Zhou, Zhi Xie, Fengchun Hu, Shiqiang Wei, I Nowik, I Felner, Lei Zhang, Zhu-An Xu, Fu-Chun Zhang
Faculty of Engineering - Papers (Archive)
We have studied a quinary Fe-based superconductor Sr2VFeAsO3 by the measurements of x-ray diffraction, x-ray absorption, Mössbauer spectrum, resistivity, magnetization, and specific heat. This apparently undoped oxyarsenide is shown to be self-doped via electron transfer from the V3+ ions. We observed successive magnetic transitions within the VO2 layers: an antiferromagnetic transition at 150 K followed by a weak ferromagnetic transition at 55 K. The spin orderings within the VO2 planes are discussed based on mixed valence of V3+ and V4+.
Structural And Superconducting Properties Of Lafeas1-Xsbxo1-Yfy, Cao Wang, Zhifeng Ma, Shuai Jiang, Yuke Li, Zhu-An Xu, Guanghan Cao
Structural And Superconducting Properties Of Lafeas1-Xsbxo1-Yfy, Cao Wang, Zhifeng Ma, Shuai Jiang, Yuke Li, Zhu-An Xu, Guanghan Cao
Faculty of Engineering - Papers (Archive)
We report the antimony (Sb) doping effect in a prototype system of iron-based superconductors LaFeAsO1−y F y (y=0, 0.1, 0.15). X-ray powder diffraction indicates that the lattice parameters increase with Sb content within the doping limit. Rietveld structural refinements show that, with the partial substitution of Sb for As, the thickness of the Fe2As2 layers increases significantly, whereas that of the La2O2 layers shrinks simultaneously. So a negative chemical pressure is indeed “applied” to the superconducting-active Fe2As2 layers, in contrast to the effect of positive chemical pressure …
Superconducting Transition Width Under Magnetic Field In Mgb2 Polycrystalline Samples, C.C Wang, R Zeng, Xun Xu, S. X. Dou
Superconducting Transition Width Under Magnetic Field In Mgb2 Polycrystalline Samples, C.C Wang, R Zeng, Xun Xu, S. X. Dou
Faculty of Engineering - Papers (Archive)
A systematic study on the superconducting transition width as a function of the applied magnetic field was performed in polycrystalline MgB2. A quantitative, yet universal relation between the two parameters was observed in all of the ceramics. It was found that the width decreases linearly with decreasing field in pure MgB2 samples. Whereas, samples with boron and/or Mg atoms partially replaced by other elements show this linear relation in the temperature range below 0.7–0.8 of the superconducting transition temperature (corresponding to a field of about 2 T), at temperatures higher than this range, an abnormal upturn in …
Extended Dislocation-Based Pinning Mechanism In Superconducting Yba2cu3o7 Films, Serhiy Pysarenko, Alexey V. Pan, S X. Dou, Rashmi Nigam
Extended Dislocation-Based Pinning Mechanism In Superconducting Yba2cu3o7 Films, Serhiy Pysarenko, Alexey V. Pan, S X. Dou, Rashmi Nigam
Faculty of Engineering - Papers (Archive)
To describe the critical current density (Jc) as the function of applied magnetic field (Ba) in high quality YBa2Cu3O7 (YBCO) superconducting films, the vortex pinning mechanism along the structural domain boundaries of the films is developed. The boundaries, assumed to have low misorientation angles, are quantitatively considered to consist of individual edge dislocations acting as pinning wells, rather than a continuous boundary. This extended model accurately describes the experimental Jc(Ba) over the wide field and temperature ranges. Marginal deviations of the model from the …
Anisotrophic Currents And Flux Jumps In High-Tc Superconducting Films With Self-Organized Arrays Of Planar Defects, V Yurchenko, A.J Qviller, P.B Mozhaeva, J.E Mozhaeva, J.B Hansen, C Jacobsen, I.M Kotelyanskii, Alexey V. Pan, T H. Johansen
Anisotrophic Currents And Flux Jumps In High-Tc Superconducting Films With Self-Organized Arrays Of Planar Defects, V Yurchenko, A.J Qviller, P.B Mozhaeva, J.E Mozhaeva, J.B Hansen, C Jacobsen, I.M Kotelyanskii, Alexey V. Pan, T H. Johansen
Faculty of Engineering - Papers (Archive)
Regular arrays of planar defects with a period of a few nanometers can be introduced in superconducting YBa2Cu3O7-δ (YBCO) thin films by depositing them on vicinal (also called miscut or tilted) substrates. This results in the anisotropy of critical currents flowing in the plane of the film. We present results of real-time magneto-optical imaging (MOI) of magnetic flux distribution and dynamics in a series of YBCO thin films deposited on NdGaO3 substrates with different miscut angles θ. MOI allows reconstructing the current flow profiles. From the angle formed between domains with different …