Abstract
To investigate the quantum tunneling of almost macroscopic vortex segments we measured the normalized relaxation rate Q of superconducting currents for various high- Tc superconductors (HTS’s) down to 100 mK in magnetic fields up to 7 T. At fields below ?0.5 T, Q is essentially independent of T in the temperature regime between thermally activated and quantum motion as theoretically expected. However, at higher fields, we find an unexpected linear T dependence of Q persisting down to the lowest temperatures in all investigated samples. Since these compounds were chosen to represent the distinct classes of dirty and clean HTS’s, the extrapolated Q(T=0) values are used to discuss the theoretical models for quantum creep in the clean and dirty limits. Based on this discussion we propose a semiempirical interpolation formula for Q(T=0) which is also valid for compounds in between the dirty and clean limits.
Original language | English |
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Pages (from-to) | 7222-7237 |
Number of pages | 16 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 59 |
Issue number | 10 |
DOIs | |
Publication status | Published - 1999 |
Externally published | Yes |