### 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 |

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### All Science Journal Classification (ASJC) codes

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

### 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

**A theory of thermal-fluctuation-induced depinning line in weakly pinning high-T _{c} superconductors.** / Yamafuji, K.; Fujiyoshi, T.; Toko, K.; Matsuno, T.; Kishio, K.; Matsushita, T.

Research output: Contribution to journal › Article

_{c}superconductors',

*Physica C: Superconductivity and its applications*, vol. 212, no. 3-4, pp. 424-434. https://doi.org/10.1016/0921-4534(93)90610-3

_{c}superconductors. Physica C: Superconductivity and its applications. 1993 Jul 15;212(3-4):424-434. https://doi.org/10.1016/0921-4534(93)90610-3

}

TY - JOUR

T1 - A theory of thermal-fluctuation-induced depinning line in weakly pinning high-Tc superconductors

AU - Yamafuji, K.

AU - Fujiyoshi, T.

AU - Toko, K.

AU - Matsuno, T.

AU - Kishio, K.

AU - Matsushita, T.

PY - 1993/7/15

Y1 - 1993/7/15

N2 - The expression for the thermal-fluctuation-induced depinning line, T = TP (Be), is derived theoretically for weakly pinning high-Tc superconductors. In the derivation, it is shown that the thermal displacement of pinned fluxoids, uth reduces the critical current density as Jc = Jc0 ( - 〈u2th〉/d2p) 3 2, where Jc0 is the critical current density in the absence of uth and dp is the effective half width of the summed-up pinning potential. Then Tp (itBe) is determined as the temperature at which Jc becomes zero due to the increase of 〈u2th〉 with the increase of T in the external flux density of Be. The relation of Tp(Be) with the irreversibility line of Ti(Be) and the flux melting line of Tm(Be) is also discussed.

AB - The expression for the thermal-fluctuation-induced depinning line, T = TP (Be), is derived theoretically for weakly pinning high-Tc superconductors. In the derivation, it is shown that the thermal displacement of pinned fluxoids, uth reduces the critical current density as Jc = Jc0 ( - 〈u2th〉/d2p) 3 2, where Jc0 is the critical current density in the absence of uth and dp is the effective half width of the summed-up pinning potential. Then Tp (itBe) is determined as the temperature at which Jc becomes zero due to the increase of 〈u2th〉 with the increase of T in the external flux density of Be. The relation of Tp(Be) with the irreversibility line of Ti(Be) and the flux melting line of Tm(Be) is also discussed.

UR - http://www.scopus.com/inward/record.url?scp=0027626216&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027626216&partnerID=8YFLogxK

U2 - 10.1016/0921-4534(93)90610-3

DO - 10.1016/0921-4534(93)90610-3

M3 - Article

AN - SCOPUS:0027626216

VL - 212

SP - 424

EP - 434

JO - Physica C: Superconductivity and its Applications

JF - Physica C: Superconductivity and its Applications

SN - 0921-4534

IS - 3-4

ER -