[PCP2] Physics and Chemistry2

[PCP2-14] Superconducting properties of (Y_1-xCa_x)Ba₂Cu₄O₈ films with various Ca contents

*Shuhei Yamagata¹, Ryoya Nagaura¹, Yuki Ogimoto¹, Shuhei Funaki², Masashi Miura^1,3 (1. Seikei University (Japan), 2. Shimane University (Japan), 3. JST-FOREST (Japan))

Keywords:

(Y1-xCax)Ba2Cu4O8 ((Y,Ca)124),REBCO,critical current density,depairing current density,Jc,Jd,Molten Hydroxide method

The critical current density (J_c), the superconducting transition temperature (T_c) and the upper critical field (μ₀H_c2) are important parameters for superconducting applications. Recently, we have reported that an improvement in the depairing current density (J_d ∝ 1/λ_ab²ξ_ab) is an effective way to improve J_c for (Y_0.77Gd_0.23)Ba₂Cu₃O_y ((Y,Gd)123) and SmFeAs(O_1-xH_x) (Sm1111) [1,2]. To clarify the effect of J_d on J_c for other superconductors, we are now interested in (Y_1-xCa_x)Ba₂Cu₄O₈ ((Y,Ca)124), because it has relatively high T_c over 85 K, and the thermodynamic parameters, such as λ_ab and ξ_ab, can be changed by varying its Ca doping level [3].In this work, to study the effect of Ca content on the superconducting properties for (Y,Ca)124, we fabricated (Y,Ca)124 thin films with various Ca content on NdGaO₃ single-crystal substrates using the low-temperature liquid-phase growth method (Molten Hydroxide method) [4]. The T_c and the μ₀H_c2 increased with increasing Ca content up to x = 0.1, implying that in this work (Y,Ca)124 films with Ca content of x = 0.1 might have higher J_d and J_c compared to those of (Y,Ca)124 films with x < 0.1. Detailed superconducting properties for (Y,Ca)124 films with different Ca contents will be presented.