### Abstract

The expression for the thermal-fluctuation-induced depinning line, T = T_{P} (B_{e}), is derived theoretically for weakly pinning high-T_{c} superconductors. In the derivation, it is shown that the thermal displacement of pinned fluxoids, u_{th} reduces the critical current density as J_{c} = J_{c0} ( - 〈u^{2}_{th}〉/d^{2}_{p})^{ 3 2}, where J_{c0} is the critical current density in the absence of u_{th} and d_{p} is the effective half width of the summed-up pinning potential. Then T_{p} (itB_{e}) is determined as the temperature at which J_{c} becomes zero due to the increase of 〈u^{2}_{th}〉 with the increase of T in the external flux density of B_{e}. The relation of T_{p}(B_{e}) with the irreversibility line of T_{i}(B_{e}) and the flux melting line of T_{m}(B_{e}) is also discussed.

Original language | English |
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Pages (from-to) | 424-434 |

Number of pages | 11 |

Journal | Physica C: Superconductivity and its applications |

Volume | 212 |

Issue number | 3-4 |

DOIs | |

Publication status | Published - Jul 15 1993 |

### All Science Journal Classification (ASJC) codes

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering

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## Cite this

_{c}superconductors.

*Physica C: Superconductivity and its applications*,

*212*(3-4), 424-434. https://doi.org/10.1016/0921-4534(93)90610-3