Presentation Information
[PC5-06-INV]Anomalous Peak Effects in Superconductors with Splayed or Tilted Columnar Defects
*Tsuyoshi Tamegai1, Wenjie Li1, Kanta Kato1, Ayumu Takahashi1, Yuto Kobayashi1, Sunseng Pyon1, Ryosuke Sakagami1, Tadashi Kambara2, Atsushi Yoshida2, Satoru Okayasu3, Ataru Ichinose4 (1. Department of Applied Physics, The University of Tokyo (Japan), 2. Nishina Center, RIKEN (Japan), 3. Advanced Science Research Center, Japan Atomic Energy Agency (Japan), 4. Central Research Institute of Electric Power Industry, Electric Power Engineering Research Laboratory (Japan))
Keywords:
Columnar Defects,Critical Current Density,Anomalous Peak Effect,Iron-based Superconductors,NbSe2
The maximum current density that superconductors can carry without dissipation, known as critical current density (Jc), can be enhanced significantly by introducing defects in superconductors. Such defects can be created chemically, through elemental substitution, or physically, via high-energy particle irradiation. When the irradiation energy is sufficiently high, it produces linear tracks known as columnar defects (CDs). Due to their geometric alignment with vortices, CDs serve as highly effective pinning centers [1]. Unlike point defects formed by light-particle irradiation, CDs offer additional control through their orientation relative to the crystal axis or external magnetic field. Theoretically, dispersing the direction of CDs (splayed CDs) can further enhance Jc [2], and this has been experimentally demonstrated in YBa2Cu3O7-δ [3]. The enhancement of Jc due to CDs is field-dependent and often exhibits an anomalous peak, known as the anomalous peak effect (APE), around ~1/3BΦ. Here, BΦ is the dose-equivalent matching field, defined as BΦ = nΦ0 (n: areal density of CDs; Φ0: flux quantum) [1,4]. APE was first clearly observed in (Ba,K)Fe2As2 when two sets of CDs were introduced symmetrically about the c-axis [4]. This effect weakens when asymmetries are introduced—either in the configuration or density of the two CD species, or by tilting the applied magnetic field away from the symmetric direction [5]. A similar APE was later reported in the conventional layered superconductor NbSe2 when CDs were introduced at an angle to the c-axis [6]. We have also confirmed APE in iron-based superconductors (IBSs) with tilted CDs [7] and in NbSe2 with splayed CDs [8].
In this talk, we summarize the present status of APE in IBSs and NbSe2 with various configurations and densities of CDs.
References
1) L. Civale et al., Phys. Rev. Lett. 67, 648 (1991).
2) T. Hwa et al., Phys. Rev. Lett. 71, 3545 (1993).
3) L. Krusin-Elbaum et al., Phys. Rev. Lett. 76, 2563 (1996).
4) A. Park et al., Phys. Rev. B 97, 064516 (2018).
5) A. Takahashi et al., J. Phys. Soc. Jpn. 89, 094705 (2020).
6) S. Eley et al., Sci. Rep. 8, 13162 (2018).
7) K. Kato et al., J. Phys. Soc. Jpn. 93, 074704 (2024).
8) W. J. Li et al., Supercond. Sci. Technol. 36, 115018 (2023).
In this talk, we summarize the present status of APE in IBSs and NbSe2 with various configurations and densities of CDs.
References
1) L. Civale et al., Phys. Rev. Lett. 67, 648 (1991).
2) T. Hwa et al., Phys. Rev. Lett. 71, 3545 (1993).
3) L. Krusin-Elbaum et al., Phys. Rev. Lett. 76, 2563 (1996).
4) A. Park et al., Phys. Rev. B 97, 064516 (2018).
5) A. Takahashi et al., J. Phys. Soc. Jpn. 89, 094705 (2020).
6) S. Eley et al., Sci. Rep. 8, 13162 (2018).
7) K. Kato et al., J. Phys. Soc. Jpn. 93, 074704 (2024).
8) W. J. Li et al., Supercond. Sci. Technol. 36, 115018 (2023).