• 한국초전도ㆍ저온공학회논문지
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• 제26권3호
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• pp.27-31
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• 2024

We fabricate high-entropy alloy (HEA) Ta_1/6Nb_2/6Hf_1/6Zr_1/6Ti_1/6 superconducting (SC) thin films via a pulsed laser deposition method. Two targets are prepared using arc melting, each followed by sintering at different temperatures: 550℃ and 700℃ for 12 hours. The films, HEA550 and HEA700, are deposited on c-cut Al₂O₃ substrates at a substrate temperature of 520℃, using the targets sintered at 550℃ and 700℃, respectively. The SC transition temperature (T_c) of HEA700 is 6.88 K, slightly higher than that of HEA550 (= 6.27 K). Both films exhibit similar upper critical field (H_c2) at 0 K, with 11.34 T for HEA550 and 11.40 T for HEA700. Notably, HEA700 exhibits a large critical current density (J_c) of approximately 4.4 MA/cm² and 3.5 MA/cm² at 2.0 K and 4.2 K, respectively, accompanying by a predominance of normal point pinning. These results indicate that the targets prepared by arc melting are beneficial for achieving a large J_c in HEA SC thin films, thus providing new avenues for improving SC critical properties of HEA thin films for their practical applications.