| 1. |
- Johansen, T.H., et al.
(författare)
-
Transition from elastic to dissipative motion in a magnet-high-Tc superconductor system
- 1991
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 70:12, s. 7496-7499
-
Tidskriftsartikel (refereegranskat)abstract
- Using quasistatic harmonic excitations, we have measured the lateral force between a permanent magnet and a Bi-based ceramic high-Tc superconductor (HTSC) for lateral displacement amplitudes down to 1 µm. We find clear evidence for a transition from elastic (nondissipative) to inelastic interaction, and attribute the effect to flux pinning. The crossover amplitude can easily reach several micrometers, with the consequence that the lateral disturbance of a levitated magnet will decay to this amplitude, whereas further damping will be extremely slow. For applications of HTSCs in magnetic bearing systems this can be a very relevant aspect of the interaction, and it can set the limit for precision positioning of levitated objects
|
|
| 2. |
- Koblischka, M. R., et al.
(författare)
-
Magneto-optic imaging of flux penetration into an artificially granular high-Tc superconductor
- 1999
-
Ingår i: Advances in Superconductivity XI. Proceedings of the 11th International Symposium on Superconductivity (ISS'98). - 4431702563 ; 2, s. 693-696
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A YBa2Cu3O7- (YBCO) thin film is patterned into a hexagonal close packed lattice of disks which are touching each other at the circumferences in order to enable the flow of an intergranular current. Such a sample was suggested by Koblischka et al. [Appl. Phys. Lett 70, 514 (1997)] as a model for a layered granular structure like in a Bi2Sr2Ca2Cu3O10- tape. Magnetization measurements reveal an anomalous position of the low field peak (central peak) similar to the tapes. Magneto-optic imaging is employed to visualize the local field distributions
|
|
| 3. |
- Koblishka, M. R., et al.
(författare)
-
Flux penetration into an artificially granular high-Tc superconductor
- 1999
-
Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 59, s. 12114-20
-
Tidskriftsartikel (refereegranskat)abstract
- A YBa2Cu3O7- thin film is patterned into a hexagonal close-packed lattice of disks (2r=50 m) which are touching each other at the circumferences in order to enable the flow of an intergranular current. Such a sample was suggested by Koblischka et al. [Appl. Phys. Lett. 70, 514 (1997)] as a model for a layered granular structure like in a (Pb,Bi)2Sr2Ca2Cu3O10+ (Bi-2223) tape. The magnetization measurements reveal an anomalous position of the low-field peak (central peak) similar to Bi-2223 tapes. Magneto-optic imaging is employed to visualize the local-field distributions. At low magnification, the flux patterns in the intergranular area between the disks are observed. The observations at high magnification reveal the flux penetration and pinning within the disks. It is shown that such samples may serve as model samples for granular high-Tc superconductors
|
|
| 4. |
- Yang, Z.J., et al.
(författare)
-
Study of flux motion in Bi-based superconductors by a pendulum
- 1992
-
Ingår i: Journal of Superconductivity. - 0896-1107 .- 1572-9605. ; 5:2, s. 127-135
-
Tidskriftsartikel (refereegranskat)abstract
- Using a computerized mechanical pendulum, we have studied the lateral magnetic flux motion of the Bi-based high-T c superconductors in the quasi-static magnetic field (0.1 Hz) for the range 1 μm to 0.35 mm. The effect of d.c. and a.c. transport currents on the flux motion has also been investigated. We argue that the lateral magnetic stiffness is a measure of the pinning potential of the fluxoids in the superconductors. The pinning energy barrier ε is estimated to be about 0.3 eV based on the stiffness measurements, which is comparable with the data from the YBa2Cu3O7-χ superconductors.
|
|
