Thermodynamic approach for enhancing superconducting critical current performance

• Published in: arXiv.org
• Main Authors: Miura, Masashi, Tsuchiya, Go, Harada, Takumu, Sakuma, Keita, Kurokawa, Hodaka, Sekiya, Naoto, Kato, Yasuyuki, Yoshida, Ryuji, Kato, Takeharu, Nakaoka, Koichi, Izumi, Teruo, Nabeshima, Fuyuki, Maeda, Atsutaka, Okada, Tatsumori, Awaji, Satoshi, Civale, Leonardo, Maiorov, Boris
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 21.10.2022
• Subjects: Carrier density; Coherence length; Conductors; Critical current density; Extreme values; Gadolinium; Nanoparticles; Optimization; Penetration depth; Physics - Superconductivity; Pinning; Superconducting magnets; Superconductivity; Superconductors; Thermodynamics
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2210.11688

The addition of artificial pinning centers has led to an impressive increase in critical current density (\(J_{\rm c}\)) in a superconductor, enabling record-breaking all-superconducting magnets and other applications. \(J_{\rm c}\) has reached \(\sim 0.2\)-\(0.3\) \(J_{\rm d}\), where \(J_{\rm d}\) is the depairing current density, and the numerical factor depends on the pinning optimization. By modifying \(\lambda\) and/or \(\xi\), the penetration depth and coherence length, respectively, we can increase \(J_{\rm d}\). For (Y\(_{0.77}\)Gd\(_{0.23}\))Ba\(_2\)Cu\(_3\)O\(_y\) ((Y,Gd)123) we achieve this by controlling the carrier density, which is related to \(\lambda\) and \(\xi\). We also tune \(\lambda\) and \(\xi\) by controlling the chemical pressure in the Fe-based superconductors, BaFe\(_2\)(As\(_{1-x}\)P\(_x\))\(_2\) films. The variation of \(\lambda\) and \(\xi\) leads to an intrinsic improvement of \(J_{\rm c}\), via \(J_{\rm d}\), obtaining extremely high values of \(J_{\rm c}\) of \(130\) MA/cm\(^2\) and \(8.0\) MA/cm\(^2\) at \(4.2\) K, consistent with an enhancement of \(J_{\rm d}\) of a factor of \(2\) for both incoherent nanoparticle-doped (Y,Gd)123 coated conductors (CCs) and BaFe\(_2\)(As\(_{1-x}\)P\(_x\))\(_2\) films, showing that this new material design is useful to achieving high critical current densities for a wide array of superconductors. The remarkably high vortex-pinning force in combination with this thermodynamic and pinning optimization route for the (Y,Gd)123 CCs reached \(\sim 3.17\) TN/m\(^3\) at \(4.2\) K and 18 T (\({\bf H}\parallel c\)), the highest values ever reported in any superconductor.