dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

摘要: dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves the response were studied on as-prepared patterned samples in fields parallel to cylinder axis. A row micron-sized antidots (holes) was made film along Avalanche-like jumps magnetization observed for both at low temperatures not only above $H_{c1}$, but lower than $H_{c1}$ vortex-free region. The positions reproducible they change from one experiment another, resembling vortex lattice instabilities usually larger $H_{c1}$. At $0.66T_c$ $0.78T_c$ become smooth samples, respectively. curve reference planar field geometry does exhibit entire range accessible temperatures. measured constant swept modes. Experiment shows that losses mode smaller sample. For shapes dependences amplitude third harmonic same near $H_{c3}$. This similarity exist mode.