Abstract
Magnetic relaxation and I-V characteristics of YBCO films with a thickness ranging from 2.4 to 200 nm have been studied. Magnetic relaxation measurements show strong quantum tunnelling effects at temperatures as high as T-cr = 8.5-15 K in ultra-thin films (2.4-40 nm), whereas in 200 nm film it is dominated by thermal activation down to 4.2 K. The high T-cr of ultra-thin films is interpreted using Blatter's dissipative tunnelling theory. The strong quantum fluctuations in the ultra-thin films are explained by their large normal state resistivity and higher activation energy compared to thicker films.
| Original language | English |
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| Pages (from-to) | 1300-1303 |
| Number of pages | 4 |
| Journal | Superconductor Science & Technology |
| Volume | 15 |
| Issue number | 9 |
| Early online date | 24 Jul 2002 |
| DOIs | |
| Publication status | Published - 1 Sept 2002 |