Designing high-performance superconductors with nanoparticle inclusions: comparisons to strong pinning theory
| Autor: | Masashi Miura, Ryuji Yoshida, Sarah C. Jones, Serena Eley, Roland Willa, Takeharu Kato, Leonardo Civale |
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| Rok vydání: | 2021 |
| Předmět: |
Superconductivity
Materials science Condensed matter physics Physics QC1-999 Condensed Matter - Superconductivity General Engineering Nanoparticle FOS: Physical sciences Coherence length Magnetic field Vortex Superconductivity (cond-mat.supr-con) Matrix (mathematics) Consistency (statistics) Condensed Matter::Superconductivity Dissipative system General Materials Science ddc:530 TP248.13-248.65 Biotechnology |
| Zdroj: | APL Materials, Vol 9, Iss 9, Pp 091105-091105-11 (2021) APL materials, 9 (9), Art. Nr.: 091105 |
| ISSN: | 2166-532X |
| DOI: | 10.48550/arxiv.2105.10204 |
| Popis: | One of the most promising routes for achieving unprecedentedly high critical currents in superconductors is to incorporate dispersed, non-superconducting nanoparticles to control the dissipative motion of vortices. However, these inclusions reduce the overall superconducting volume and can strain the interlaying superconducting matrix, which can detrimentally reduce $T_c$. Consequently, an optimal balance must be achieved between the nanoparticle density $n_p$ and size $d$. Determining this balance requires garnering a better understanding of vortex-nanoparticle interactions, described by strong pinning theory. Here, we map the dependence of the critical current on nanoparticle size and density in (Y$_{0.77}$,Gd$_{0.23}$)Ba$_2$Cu$_3$O$_{7-\delta}$ films in magnetic fields up to 35 T, and compare the trends to recent results from time-dependent Ginzburg-Landau simulations. We identify consistencies between the field-dependent critical current $J_c(B)$ and expectations from strong pinning theory. Specifically, we find that that $J_c \propto B^{-\alpha}$, where $\alpha$ decreases from $0.66$ to $0.2$ with increasing density of nanoparticles and increases roughly linearly with nanoparticle size $d/\xi$ (normalized to the coherence length). At high fields, the critical current decays faster ($\sim B^{-1}$), suggestive that each nanoparticle has captured a vortex. When nanoparticles capture more than one vortex, a small, high-field peak is expected in $J_c(B)$. Due to a spread in defect sizes, this novel peak effect remains unresolved here. Lastly, we reveal that the dependence of the vortex creep rate $S$ on nanoparticle size and density roughly mirrors that of $\alpha$, and compare our results to low-$T$ nonlinearities in $S(T)$ that are predicted by strong pinning theory. |
| Databáze: | OpenAIRE |
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